The purpose of this thesis is to investigate the concept of a work and the problems with its definition and will also examine bibliographic relationships. The main question is what are the boundaries of a work and at what point a work becomes another. What is the meaning of the concept of a work within the context of the library? What are the solutions of bibliographic relationships and the concept of a work in KRS and FRBR? The thesis is based on a literature review. In the literature I have examined the discussions of the work and bibliographic relationships. I made a comparison between the Swedish cataloguing standard of today, KRS, the suggestion of future cataloguing, FRBR and the catalogue of the Düben Collection. The empirical examples were taken from the Düben Collection, which contains musical works of the Swedish Royal Court from the 17th and early 18th century. The collection has been available since 2006 in a database catalogue on the Internet. I have examined works of six composers, which exist in the catalogue in at least two manifestations. The result of this study shows that the problem with the boundaries of a work is not solved and this is a subjective problem. Cataloguing performed according to the KRS, collocate different versions of a work and its related works, using uniform titles and bibliographic relationships. FRBR offers great opportunities to collocate the different versions of a work, but it is still a suggestion, implemented in just a few web-based resources. / Uppsatsnivå: D