MLA

Backus, Isaac, 1724-1806. Collected papers. Box 7, folder 35. 1754 June-September. https://collections.library.yale.edu/catalog/33554275.

APA, 6th edition

Backus, Isaac, 1724-1806. (["Box 7, folder 35"])(1754 June-September)[Collected papers]. https://collections.library.yale.edu/catalog/33554275.