MLA

Boswell, James, 1740-1795. Advertisements (P 99). Box 64, folder 1324. 1787. https://collections.library.yale.edu/catalog/2039312.

APA, 6th edition

Boswell, James, 1740-1795. (["Box 64, folder 1324"])(1787)[Advertisements (P 99)]. https://collections.library.yale.edu/catalog/2039312.