Relating to the connection between information science and bibliography (and librarianship), the elements are given to compare the concepts of Répertoire Bibliographique Universel (RBU) and COBIB within the COBISS system. Different aspects of understanding the development of bibliographies and the author’s personal view of the development of bibliographies are presented. According to Paul Otlet’s idea, conceived at the end of the 19th century, RBU was to represent the universal bibliography of all books and other publications from all countries, from all times and from all subject areas, organised by subject and author. Catalogues should represent the first stage of RBU.