The master thesis represents the usage from bibliographic records in COBIB, based on Resource description and access (RDA) core elements. In theoretical part RDA is shown, as well as their evolution, structure, aims, principles and the main changes that they bring. The COBIB database is briefly described in thesis. We were interested to know which bibliographic data were most commonly searched by users and librarians in public or academic libraries, if bibliographic data matches with RDA core elements, as well as if there is a difference between librarians and users searching results. We presented a research, which we carried aout with questionnaire and observing thinking aloud. The research showed that users and librarians most commonly search with RDA core elements (title and author), but few elements, that RDA doesn’t indicate them as core elements (for example subject headings …), should be added. Research shows that the RDA core elements are more commonly used by librarians than users.