MLA

Backus, Isaac, 1724-1806. The testimony of the two witnesses, explained and vindicated, with a few remarks upon the late writings of Dr. Hemmenway and Dr. Lathrop. Box 5, folder 12. 1793. https://collections.library.yale.edu/catalog/33531014.

APA, 6th edition

Backus, Isaac, 1724-1806. (["Box 5, folder 12"])(1793)[The testimony of the two witnesses, explained and vindicated, with a few remarks upon the late writings of Dr. Hemmenway and Dr. Lathrop]. https://collections.library.yale.edu/catalog/33531014.