Cite

3 autograph letters, signed, to unidentified correspondents

MLA

3 Autograph Letters, Signed, to Unidentified Correspondents. 21AD. https://collections.library.yale.edu/catalog/32300539.

APA, 6th edition

3 autograph letters, signed, to unidentified correspondents. (21 C.E.). https://collections.library.yale.edu/catalog/32300539.