MLA

Pratt, Richard Henry, 1840-1924. Vilas, William Freeman, 5 items. Box 9, folder 308. 1888-93, n.d.. https://collections.library.yale.edu/catalog/16701080.

APA, 6th edition

Pratt, Richard Henry, 1840-1924. (["Box 9, folder 308"])(1888-93, n.d.)[Vilas, William Freeman, 5 items]. https://collections.library.yale.edu/catalog/16701080.