In 1548 Conrad Gessner (Gesner) issued from Zurich Pandectarum sive Partitionum universalium libri XXI. Pandectarum was the first general subject index, which Gessner intended as a key to his Bibliotheca Universalis (1545).
According to Ruth French Strout's "The Development of the Catalog and Cataloging Codes," Library Quarterly 26 (1956) 263 Gessner included in the Pandectarum
"instructions for the arrangement of books in a library, and he conceived of his system of classification for library as well as for bibliographical purposes. He even suggested that libraries use copies of his bibliographies as their catalogues by inserting call numbers beside entries which represented their holdings, thus providing themselves with both an author and a subject catalogue."
Breslauer & Folter, Bibliography: Its History and Development  no. 16).
Besterman, The Beginnings of Systematic Bibliography 2nd ed (1940) no. XVII.
Digital facsimile of the first edition from e-rara.ch at this link.