MLA

Gardner, G. Clinton (George Clinton), 1834-1904. G. Clinton Gardner papers, 1854-1868. https://collections.library.yale.edu/catalog/2054814.

APA, 6th edition

Gardner, G. Clinton (George Clinton), 1834-1904. [G. Clinton Gardner papers, 1854-1868]. https://collections.library.yale.edu/catalog/2054814.