MLA

Pforzheimer, Walter L. (Walter Lionel), 1914-2003. Church, R. Benjamin. Box 17. 1775. https://collections.library.yale.edu/catalog/17290898.

APA, 6th edition

Pforzheimer, Walter L. (Walter Lionel), 1914-2003. (["Box 17"])(1775)[Church, R. Benjamin]. https://collections.library.yale.edu/catalog/17290898.