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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Semiotic Approach in the Development of Interactive Visual Analytics Systems*</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Bryansk State Technical University</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Bryansk</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Russia zaa@tu-bryansk.ru</string-name>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Tomsk Polytechnic University</institution>
          ,
          <addr-line>Tomsk</addr-line>
          ,
          <country country="RU">Russia</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>Increasing information saturation in all spheres of life entails accumulation of large amounts of data that must be perceived, processed and decisions must be made on their basis. Therefore, the issues of interaction with data and of visual analytics require solutions at a new level. The authors investigate communication between the user and the data, highlight a number of negative trends that prevent effective use of visualization in solving practical problems, formulate aspects of subjective influence on the decision-making procedure, namely those leading to significant decrease in the efficiency of visual analytics systems. The paper proposes an approach to the problem of reasonable use of existing and potential visualization capabilities for solving data analysis problems and making control decisions. A significant factor hindering the development of visual analytics is a lack of a model for coordinated use of computational and subjective resources corresponding to the technical level of computer visualization capable of ensuring close communication between the researcher and the available data. The paper describes an approach based on the concept of visual communication, the properties of which are determined on the basis of a number of key concepts of semiotics and linguistics.</p>
      </abstract>
      <kwd-group>
        <kwd>Visualization</kwd>
        <kwd>Semiotics</kwd>
        <kwd>Visual Communication</kwd>
        <kwd>Data Analysis</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>The continuously increasing saturation of information environment of our time is a
factor influencing the effectiveness of use of new data and knowledge both in
everyday life and in scientific research. The availability of up-to-date digital data as well as
the possibility of their (practically) unlimited preservation, at a certain stage, made</p>
      <p>The reported study was funded by RFBR, project number 19-07-00844.
vital the task of preliminary analysis, data formalization, aimed at extracting new
knowledge and reducing the amount of information involved in decision-making
procedures for solving control problems in real scientific and production processes.</p>
      <p>In practice, many existing approaches to the formalized data presentation provoke
one of the possible negative situations. On the one hand, a simplified representation of
data used to increase the speed of decision making leads to distancing of the decision
maker from the initial data and makes the resulting solution dependent on subjective
experience and knowledge, as well as on the correctness of the formalized
representation. In the opposite case, tools are used to ensure the availability of both the initial
data and the results of their subsequent analysis. For situations involving generation
of many alternative decision hypotheses and their subsequent verification, the use of
such tools can significantly increase the amount of analyzed data and, as a result,
complicate the final decision.</p>
      <p>Additional circumstances, that often make a significant contribution to the
efficiency of data analysis and making control decisions based on it, are simultaneous
participation of more than one subject in this process and the necessity for selecting
the most attractive decision hypothesis on the basis of joint analysis of data related to
different subject areas and accumulated knowledge. In this case, the conflict of
opinions becomes an obstacle, overcoming of which depends on circumstances that go
beyond the boundaries of the current problem, for example, on coordination of
participants’ competencies or the priority of their opinions.
2</p>
    </sec>
    <sec id="sec-2">
      <title>Interaction with data</title>
      <p>
        Technologies for solving applied problems associated with the use of machine
learning capabilities as a basis for making a final decision are deliberately left out of the
discussion [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ]. This is due to the need for development of technologies applicable to
the analysis of non-standard data, including for prompt forecasting of the state of
analyzed systems or for using new data that were not initially taken into account in
the formal model of these systems. Thus, obtaining the required answer in data
analysis tasks is considered as a result of subjective interaction of a conditional user
(group) with a certain amount of data having a heterogeneous level of
formalization [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ].
      </p>
      <p>
        Upon close examination, communication between the user and the data appears to
be a poorly researched process, despite the fact that it is mandatory for analytical tools
of any type. The increasing complexity of analysis problems and tools proposed for
their solution leads to the emergence of significant requirements for methods of such
communication including their implementation in the form of HCI (human-computer
interface) tools. Proliferation of computer systems for data processing and analysis is
gradually forming an expanding community of users who employ a specialized
communication system to interact with information environment [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ].
      </p>
      <p>A distinctive feature of the development of such a system is borrowing ways of
presenting information that are characteristic of other types of human activity. The
variety of acceptable representation methods is based on the use of all possible
senso</p>
      <p>Semiotic Approach in the Development of Interactive Visual Analytics Systems 3
ry types and their combinations. This enables transfer of various types of data that
satisfies constraints of a specific task including achieving a desired transfer rate,
interpretation time, the need to employ user experience and any others. Visualization
tools are still the most common variant of technical solutions in the development of
data analysis tools, because visual perception is rightly believed to have a number of
necessary advantages. However, further progress in this direction depends on the
answers to several questions.
3</p>
    </sec>
    <sec id="sec-3">
      <title>Visualization problems</title>
      <p>
        Review of existing and emerging data visualization tools, especially those used in
science, social process management or business analytics [4; 5], allow recognizing a
number of negative tendencies that impede the effective use of visualization in
solving practical problems.
1. Application of many modern technical developments in the field of computer
visualization is more caused by the need for their commercial promotion than the
achievable effectiveness.
2. The developed HCI tools use conceptual solutions proposed many years ago and
probably do not correspond to the increased complexity level of information
communication tasks [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ].
3. Peculiarities of communication between the user and the visualized data are
described by regularities reliability of which needs to be clarified due to the
introduction of technical means that implement new and significantly different conditions
of visual perception.
4. The set of perception peculiarities (perceptual portrait) of a potential user of
visualization tools, the level of his preliminary awareness and practical cognitive models
(understanding of which is necessary to select the most adequate means of data
presentation) are constantly changing.
5. Reactions of the user of visualization tools, control of his emotional state and the
directed use of perceptual psychology are unemployed reserves of visual analytics
tools.
6. Active private use of computer and information technologies transforms the
conceptual apparatus and reliability criteria belonging to the user, which can affect
interpretation of visualized data [7; 8].
7. Developers of visualization systems provide the user with an opportunity to choose
a unique way of presenting data according to a set of preferences relevant to him;
this leads to the need for this user to receive specialized training.
      </p>
      <p>
        Thus, the development of visual data representation tools intended for the user to
obtain a solution to a certain practical analysis problem requires a formalized
description of communication between the user and the visualized data (hereinafter, visual
communication) [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ]. Availability of such a description will allow to determine the
features of visual representation that maximize its potential through reasonable and
purposeful use.
4
      </p>
    </sec>
    <sec id="sec-4">
      <title>Visual communication</title>
      <p>Special attention should be paid to the subjective side of visual communication with
the analyzed data, since it determines the features of the achieved result, which
distinguish the use of visual analytics from the use of machine learning tools. There are
several aspects of subjective influence on the final decision-making procedure,
ignoring or mistaken use of which leads to a significant decrease in the effectiveness of
visual analytics systems:
• Uncertainty in the results of interpretation experienced by the user largely depends
on the consistency of his own data representation (internal image) and the proposed
visualization metaphor. Therefore, the use of expressive means known or
understood by the user earlier should help to overcome one of the communication
barriers.
• The procedure for verifying the information obtained as a result of visual
communication, taking into account the peculiarities of visual perception, occurs as a
multiple repetition of the search for an answer to the formulated question in an
accessible visual data image, with the consideration of new information accumulated by
the user at each step of communication. A need arises for a systematized and
operational, from the user's point of view, access to the changing volume of unverified
data.
• Doubt. The repeated procedure of comprehension (interpretation), depending on
the culture of thinking inherent in the user, can last as long as desired until the
image formed under the influence of new information is accepted as an element of the
user's knowledge system.</p>
      <p>There arises a problem of coordinating several ways of representing information:
visualization tools used for the initial data, temporary fixation of unverified versions
as well as images that are remembered and used in the future by the user as his own
knowledge.
5</p>
    </sec>
    <sec id="sec-5">
      <title>Semiotic Approach</title>
      <p>Based on definitions of a number of terms used in linguistics, developers of
visualization systems face several independent tasks that currently do not have substantiated
and complete solutions (Figure 1).</p>
      <p>Visualization sigmatics can indicate problems related to the selection or
development of visually perceptible objects designed to convey the required meaning to the
user. Visualization semantics, obviously, should determine principles of coordinated
use of available visualization technologies to form a consistent system for displaying
initial data and interpretation results. Visualization syntactics should focus on solving
problems of effective combination of visual objects integrated in data images. Finally,
visualization pragmatics corresponds to the study of peculiarities of understanding by
an observer of a visual image or their sequence, including such complex situations as</p>
      <p>Semiotic Approach in the Development of Interactive Visual Analytics Systems 5
visualization of abstract data or ideas that do not have perceptually-based
representations known to the user.
A certain paradox is obvious in the development of visualization tools and their
practical application associated with insufficient attention paid by developers to the
pragmatics of visualization. Modern technical and software solutions used by computer
visualization systems allow achieving a high level of complexity and detail of images
reproduced in various ways. However, assessment of information content and its
interpretability necessary for reasonable application of such systems cannot be obtained
on the basis of the widespread concept of visual communication as a process similar
to the functioning of communication systems.</p>
      <p>
        As a consequence of peculiarities of user perception and thinking implemented at
the time of visual communication (Figure 2), ambiguity of data visual interpretation
arises which predetermines several approaches to the use of visualization tools that
differ in tasks solved, visualization requirements and end user characteristics [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ]. It
is understood that the achievement of the goal of visual communication can occur in
different ways, but in each case it is necessary to agree on all the above aspects.
Definition of the preferred option corresponds to the use of visualization tools matching
the data interpretation task pursued, but the choice is based on a number of criteria
external to the data itself. For example, the choice of one out of many acceptable
visualization techniques may occur with a preference based not so much on the features
of the source data (format, volume, origin), but on the options familiar to the end user.
This is consistent with the pragmatics of visualization and, as a result, makes visual
communication more comfortable and effective (Figure 3).
      </p>
      <p>The established hypothetical correspondence between the concepts of linguistics and
some processes inherent in visualization functioning suggests the existence of
similarities between speech and visual communication. An important consequence of this
resemblance is preparedness of the user's thinking for the appearance in the samples
of synthesized computer visualization of expressive techniques similar to the usual
verbal communication: emotional statements, rhetorical questions, metaphors,
ambiguous images, etc. Moreover, visualization, based on the modern understanding of its
technical capabilities, can be considered as a communication option, similar to
language communication, but more capacious, multifaceted and preferential for many
practical situations.</p>
    </sec>
    <sec id="sec-6">
      <title>Development of visualization tools</title>
      <p>Focusing on the similarity between speech and visual communication, developers of
information visualization tools, used among other things in control decision support
systems, get a promising direction for the development of information visualization
tools. Its feature is structured sequential transmission to the consumer (recipient) of
information volumes that exceed the capabilities of both language messages and
traditional computer graphics. However, the achievement of this result faces at least
several problems that require special research.</p>
      <p>Firstly, the developer of visualization tools must get systematic and deep
understanding of the features of user communication with visualized information. This will
allow to move from the extensive complication of visualization tools to
communication focused on the user's perception and thinking.</p>
      <p>Secondly, the question of how to overcome the communicative barrier associated
with different levels of preliminary informing users, their cultural (including
linguistic) and physiological characteristics remains practically unexplored. Existing
visualization methods circumvent these issues by using a standardized (for historical and
economic reasons) set of expressive techniques, which is currently becoming a
negative factor that hinders the development of visual analytics.</p>
      <p>Thirdly, the need naturally arises to develop techniques for visual data
representation both borrowing effective means of verbal communication (imagery, comparisons,
metaphors, attention retention, emotional coloring) and using unique visualization
capabilities (parallel presentation; memorizing and operating not with attributes but
images; interpretation of movement, etc.). Experimental evaluation of the
effectiveness of new visualization techniques is still another independent and laborious task.</p>
      <p>
        Based on the statements made, benefits arising from independent improvement of
some characteristics of visualization tools corresponding to various aspects of the
semiotic approach have been assessed. The most significant results obtained when
solving a series of test problems for multidimensional data analysis (Table 1) are
associated with improvement in visualization pragmatics as a result of organizing
interactive communication between the user and visual analytics (Figure 4).
In addition, transition to the use of visualization systems with high information
saturation makes it more important to solve a number of problems related to perceptual
psychology. The most common of them include passivity of thinking, leading to
resistance to the new or unexpected, subjective fears and prejudices, changing
emotional background, fatigue, loss of concentration or motivation [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ].
The paper proposes an approach aimed at changing the development process of visual
analytics tools, which are currently widely used both in business processes and in
scientific research. The goal of the semiotic approach is to increase practical
efficiency of existing visualization tools by explaining and reducing the number of erroneous
results of both interpretation of visualized data and interaction of an unprepared user
with specialized information processing systems. One of the significant conclusions
obtained during the development of the semiotic approach applied to visual analytics
systems is the possibility of more active use of knowledge and experience belonging
to the user.
      </p>
    </sec>
  </body>
  <back>
    <ref-list>
      <ref id="ref1">
        <mixed-citation>
          1.
          <string-name>
            <surname>Blascheck</surname>
            ,
            <given-names>T.</given-names>
          </string-name>
          , John,
          <string-name>
            <given-names>M.</given-names>
            ,
            <surname>Kurzhals</surname>
          </string-name>
          ,
          <string-name>
            <given-names>K.</given-names>
            ,
            <surname>Koch</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            ,
            <surname>Ertl</surname>
          </string-name>
          ,
          <string-name>
            <surname>T.</surname>
          </string-name>
          :
          <article-title>VA2: A Visual Analytics Approach for Evaluating Visual Analytics Applications</article-title>
          .
          <source>IEEE Transactions on Visualization and Computer Graphics</source>
          .
          <volume>22</volume>
          (
          <issue>1</issue>
          ),
          <fpage>61</fpage>
          -
          <lpage>70</lpage>
          (
          <year>2016</year>
          ). doi:
          <volume>10</volume>
          .1109/TVCG.
          <year>2015</year>
          .2467871
        </mixed-citation>
      </ref>
      <ref id="ref2">
        <mixed-citation>
          2.
          <string-name>
            <surname>Sacha</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Sedlmair</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Zhang</surname>
            ,
            <given-names>L.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Lee</surname>
            ,
            <given-names>J.A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Weiskopf</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          , North,
          <string-name>
            <given-names>S.</given-names>
            ,
            <surname>Keim</surname>
          </string-name>
          ,
          <string-name>
            <surname>D.:</surname>
          </string-name>
          <article-title>HumanCentered Machine Learning Through Interactive Visualization: Review and Open Challenges</article-title>
          .
          <source>In: ESANN 2016 proceedings, European Symposium on Artificial Neural Networks, Computational Intelligence and Machine Learning</source>
          , pp.
          <fpage>641</fpage>
          -
          <lpage>646</lpage>
          .
          <year>i6doc</year>
          .com publ, Bruges, Belgium (
          <year>2016</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref3">
        <mixed-citation>
          3.
          <string-name>
            <surname>Massel</surname>
            <given-names>L.V.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Massel</surname>
            <given-names>A.G.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Ivanov</surname>
            <given-names>R.A.</given-names>
          </string-name>
          :
          <article-title>Integration of Visual Analytics, Cognitive Graphics and Semantic Modeling in Semiotic Intelligent Systems for Decision Support</article-title>
          . In: Proceeding of International Workshop on Contingency Management, Intelligent, AgentBased Computing and
          <article-title>Cyber Security in Critical Infrastractures CM/IA/CS/CI-2016</article-title>
          . pp.
          <fpage>19</fpage>
          -
          <lpage>22</lpage>
          . Melentiev Energy Systems Institute; Russian Academy of Science Siberian Branch, Irkutsk, Russia (
          <year>2016</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref4">
        <mixed-citation>
          4.
          <string-name>
            <surname>Crouser</surname>
            ,
            <given-names>R.J.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Franklin</surname>
            ,
            <given-names>L.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Endert</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Cook</surname>
            ,
            <given-names>K.</given-names>
          </string-name>
          :
          <article-title>Toward Theoretical Techniques for Measuring the Use of Human Effort in Visual Analytic Systems</article-title>
          .
          <source>IEEE Transactions on Visualization and Computer Graphics</source>
          .
          <volume>23</volume>
          (
          <issue>1</issue>
          ),
          <fpage>121</fpage>
          -
          <lpage>130</lpage>
          (
          <year>2017</year>
          ). doi:
          <volume>10</volume>
          .1109/TVCG.
          <year>2016</year>
          .2598460
        </mixed-citation>
      </ref>
      <ref id="ref5">
        <mixed-citation>
          5.
          <string-name>
            <surname>Batch</surname>
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Elmqvist</surname>
            ,
            <given-names>N.</given-names>
          </string-name>
          :
          <article-title>The Interactive Visualization Gap in Initial Exploratory Data Analysis</article-title>
          .
          <source>IEEE Transactions on Visualization and Computer Graphics</source>
          .
          <volume>24</volume>
          (
          <issue>1</issue>
          ),
          <fpage>278</fpage>
          -
          <lpage>287</lpage>
          (
          <year>2018</year>
          ). doi:
          <volume>10</volume>
          .1109/TVCG.
          <year>2017</year>
          .2743990
        </mixed-citation>
      </ref>
      <ref id="ref6">
        <mixed-citation>
          6.
          <string-name>
            <surname>Levontin</surname>
            <given-names>P.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Walton Jo</surname>
          </string-name>
          .L.:
          <article-title>Visualising Uncertainty: A Short Introduction</article-title>
          . AU4DM, London, UK.
          <year>2020</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref7">
        <mixed-citation>
          7.
          <string-name>
            <surname>Schofield</surname>
            <given-names>D.</given-names>
          </string-name>
          :
          <article-title>Courting the Visual Image: The Ability of Digital Graphics and Interfaces to Alter the Memory and Behaviour of the Viewer</article-title>
          . In: Kurosu M. (eds.)
          <string-name>
            <surname>Human-Computer Interaction</surname>
          </string-name>
          . Theories, Methods, and Human Issues.
          <source>HCI 2018. Lecture Notes in Computer Science</source>
          , vol
          <volume>10901</volume>
          , pp.
          <fpage>325</fpage>
          -
          <lpage>344</lpage>
          . Springer, Cham (
          <year>2018</year>
          ). doi:
          <volume>10</volume>
          .1007/978-3-
          <fpage>319</fpage>
          -91238- 7_
          <fpage>27</fpage>
        </mixed-citation>
      </ref>
      <ref id="ref8">
        <mixed-citation>
          8.
          <string-name>
            <surname>Podvesovskii</surname>
            ,
            <given-names>A.G.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Isaev</surname>
            ,
            <given-names>R.A.</given-names>
          </string-name>
          :
          <article-title>Constructing Optimal Visualization Metaphor of Fuzzy Cognitive Maps on the Basis of Formalized Cognitive Clarity Criteria</article-title>
          .
          <source>Scientific Visualization</source>
          <volume>11</volume>
          (
          <issue>4</issue>
          ),
          <fpage>115</fpage>
          -
          <lpage>129</lpage>
          (
          <year>2019</year>
          ).
          <source>doi: 10.26583/sv.11.4.10</source>
        </mixed-citation>
      </ref>
      <ref id="ref9">
        <mixed-citation>
          9.
          <string-name>
            <surname>Sacha</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Stoffel</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Stoffel</surname>
            ,
            <given-names>F.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Kwon</surname>
            ,
            <given-names>B.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Ellis</surname>
            ,
            <given-names>G.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Keim</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          :
          <article-title>Knowledge Generation Model for Visual Analytics</article-title>
          .
          <source>IEEE Transactions on Visualization and Computer Graphics</source>
          <volume>20</volume>
          (
          <issue>12</issue>
          ),
          <fpage>1604</fpage>
          -
          <lpage>1613</lpage>
          . (
          <year>2014</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref10">
        <mixed-citation>
          10.
          <string-name>
            <surname>Zakharova</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Vekhter</surname>
            ,
            <given-names>E.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Shklyar</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Zavyalov</surname>
            <given-names>D.</given-names>
          </string-name>
          :
          <article-title>Visual Detection of Internal Patterns in the Empirical Data</article-title>
          . In: Kravets A.,
          <string-name>
            <surname>Shcherbakov</surname>
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Kultsova</surname>
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Groumpos</surname>
            <given-names>P</given-names>
          </string-name>
          . (eds.)
          <article-title>Creativity in Intelligent Technologies and Data Science</article-title>
          .
          <source>CIT&amp;DS 2017. Communications in Computer and Information Science</source>
          , vol
          <volume>754</volume>
          , pp.
          <fpage>215</fpage>
          -
          <lpage>230</lpage>
          . Springer, Cham (
          <year>2017</year>
          ). doi:
          <volume>10</volume>
          .1007/978-3-
          <fpage>319</fpage>
          -65551-2_
          <fpage>16</fpage>
        </mixed-citation>
      </ref>
      <ref id="ref11">
        <mixed-citation>
          11.
          <string-name>
            <surname>Zakharova</surname>
            ,
            <given-names>A.A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Vekhter</surname>
            ,
            <given-names>E.V.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Shklyar</surname>
            ,
            <given-names>A.A.</given-names>
          </string-name>
          :
          <article-title>The Applicability of Visualization Tools in the Meta-Design of an Educational Environment</article-title>
          .
          <source>European Journal of Contemporary Education</source>
          <volume>8</volume>
          (
          <issue>1</issue>
          ),
          <fpage>43</fpage>
          -
          <lpage>51</lpage>
          (
          <year>2019</year>
          ). doi:
          <volume>10</volume>
          .13187/ejced.
          <year>2019</year>
          .
          <volume>1</volume>
          .
          <fpage>43</fpage>
        </mixed-citation>
      </ref>
    </ref-list>
  </back>
</article>