MLA

Egbert, Joseph C., and M. D. Ex Libris, Dr. Joseph C. Egbert. 0AD. https://collections.library.yale.edu/catalog/16788848.

APA, 6th edition

Egbert, J. C., & M. D. (0 C.E.). Ex Libris, Dr. Joseph C. Egbert [Bookplates]. https://collections.library.yale.edu/catalog/16788848.