The main objective of this study is to amalgamate the MARC 21 FRBRization practices with UNIMARC format semantics and to highlight some differences between them in the context of FRBRization. The main focus is to examine the possibility of using the UNIMARC link fields in order to identify the Functional Requirements for Bibliographic Records (FRBR) Work entities. In our approach we suggest that all records linked with 45X fields may belong to the same Work with the record which contains these fields. As a test set of this approach we used a sample of records of ancient Greek authors from the Union Catalogue of Hellenic Academic Libraries.