MLA

Archiquette, John, 1847-1923. Pratt, Richard Henry to Archiquette, Martin D.. Box 2, folder 37. 1915 December 31. https://collections.library.yale.edu/catalog/16715393.

APA, 6th edition

Archiquette, John, 1847-1923. (["Box 2, folder 37"])(1915 December 31)[Pratt, Richard Henry to Archiquette, Martin D.]. https://collections.library.yale.edu/catalog/16715393.