MLA

Backus, Isaac, 1724-1806. Collected papers. box 8, folder 25. 1767 May–1767 July. https://collections.library.yale.edu/catalog/33555776.

APA, 6th edition

Backus, Isaac, 1724-1806. (["box 8, folder 25"])(1767 May–1767 July)[Collected papers]. https://collections.library.yale.edu/catalog/33555776.