MLA

Remington, Frederic, 1861-1909. Letter : 301 Webster Avenue, New Rochelle, Westchester Co., N. Y., to [Howard] Pyle. Box 43, folder GROUP 732, F-1. [1895] Feb 22. https://collections.library.yale.edu/catalog/10081319.

APA, 6th edition

Remington, Frederic, 1861-1909. (["Box 43, folder GROUP 732, F-1"])([1895] Feb 22)[Letter : 301 Webster Avenue, New Rochelle, Westchester Co., N. Y., to [Howard] Pyle]. https://collections.library.yale.edu/catalog/10081319.