The purpose of this study is to gain a better understanding of the treatment of pseudonyms and anonymity in bibliographic systems for information organization. The goal of the research is to determine how catalogs handle anonymous works and those written under pseudonyms, whether the data on the identities of individuals publishing under pseudonyms or anonymously are sufficiently protected in catalogs and remain undiscovered. The theoretical part of the paper aims to elucidate whether the use of different author names poses challenges when including publications in a catalog and what is done in such situations, while respecting the protection of data about authors and the rule that the true identity must not be revealed unless the author has disclosed it themselves. Conceptual models, standards, and guidelines for bibliographic information organization are described. Special attention is given to the reasons for using pseudonyms and anonymity. The research part of the study has determined appropriate treatment of pseudonyms and anonymous entities within catalogs and databases. Specifically, it was found that data about authors who use both a pseudonym and their real identity are networked, i.e., linked within the catalog (CROLIST and ZaKi) and a more comprehensive international database (VIAF), while data about the true identity of authors who use exclusively a pseudonym or are anonymous remain undisclosed within the catalog (CROLIST and ZaKi) and the international database (VIAF).