Semantic Web technologies have provided solutions, offering significant opportunities for improving and optimizing information search and retrieval processes, especially in the bibliographic domain.

Although the representation tools used in the bibliographic universe are already consolidated, many new information resources have been created, making some guidelines obsolete. Libraries are therefore faced with the challenge of revising their representation processes and tools to make them more suitable for the new technological demands. These adjustments and updates require a review and change of theoretical and methodological paradigms, such as the use of ontologies, which are essential for organizing and representing knowledge. Ontologies define structured frameworks using classes and properties, enabling libraries to make their data more interoperable and accessible. Currently, much bibliographic data is published in formats that limit interlinking with other datasets, restricting data accessibility. Berners-Lee's core principles, along with best practices from the World Wide Web Consortium (W3C), emphasize using URIs, standard protocols, and linked data to enable discovery and connection across datasets. Libraries hold vast amounts of valuable data, but existing systems often fail to make it accessible on the Web in an open, connected format. In Brazil, no institutions have yet fully implemented Linked Open Data (LOD) practices to address these challenges. Research problem: How to structure national library data based on the principles of connected open data. The aim is to map the data and identify the processes required for the publication of connected open data by libraries. The research is ongoing and is currently in the phase of identifying the data and metadata models used by each library. Methodology: This research is characterized as qualitative, exploratory and theoretical, using the Crosswalk method, proposed by the National Information Standards Organization (NISO) in 1999, for data analysis. The Crosswalk method enables interoperability between systems that use heterogeneous metadata standards. It involves harmonization, semantic mapping, element-to-element mapping, and the organization of metadata hierarchically. The crosswalk process can encounter challenges, such as one-to-one, oneto-many, and many-to-one equivalences. To manage these challenges, a general mapping approach was adopted, focusing on the compatibility of the classes and properties proposed by each of the analyzed institutions. First, the metadata standards were mapped individually, followed by the creation of a comprehensive table that presents an overall view of all the standards. In this context, the metadata from national libraries that share linked open data were mapped.