MLA

Backus, Isaac, 1724-1806. Collected papers. box 9, folder 29. 1772 August 27–1772 September 4. https://collections.library.yale.edu/catalog/33578667.

APA, 6th edition

Backus, Isaac, 1724-1806. (["box 9, folder 29"])(1772 August 27–1772 September 4)[Collected papers]. https://collections.library.yale.edu/catalog/33578667.