MLA

Drinkwater, John, 1882-1937. Whibley, Charles, 1859-1930. 11 ALS. Box 9, folder 390. n.d.. https://collections.library.yale.edu/catalog/17280592.

APA, 6th edition

Drinkwater, John, 1882-1937. (["Box 9, folder 390"])(n.d.)[Whibley, Charles, 1859-1930. 11 ALS]. https://collections.library.yale.edu/catalog/17280592.