MLA

Backus, Isaac, 1724-1806. Numbers 11:20. Box 2, folder 14. 1770 April 2. https://collections.library.yale.edu/catalog/33553653.

APA, 6th edition

Backus, Isaac, 1724-1806. (["Box 2, folder 14"])(1770 April 2)[Numbers 11:20]. https://collections.library.yale.edu/catalog/33553653.