MLA

Backus, Isaac, 1724-1806. Collected papers. box 8, folder 23. 1766 August–1766 November. https://collections.library.yale.edu/catalog/33555745.

APA, 6th edition

Backus, Isaac, 1724-1806. (["box 8, folder 23"])(1766 August–1766 November)[Collected papers]. https://collections.library.yale.edu/catalog/33555745.