In cooperation with the Zograf Holy Monastery - Saint Great Martyr George. Mount Athos, the Sofia University Library St. Kliment Ohridski provides its users with access to the offline digital collection, the Zograf Electronic Research Library. The collection contains digital copies of Slavic manuscripts, as their originals are kept in the collections of fourteen monasteries, libraries, museums, and research organizations. The collection includes digital copies of manuscripts from the Zograf Holy Monastery - Saint Great Martyr George. This paper details the library's experience organizing and making the collection available to users. It focuses on creating metadata using MARC 21 format for digital resources in the Sofia University Library's integrated library and information system. In addition to the basic parameters of the bibliographic data format, the presentation will discuss solutions for optimizing the research descriptions of manuscripts and organizing them into a digital collection.