MLA

Hodgson, Ralph, 1871-1962. Siegfried Sassoon. Box 61, folder 1096-1097. ca. 1889-[1951]. https://collections.library.yale.edu/catalog/2007882.

APA, 6th edition

Hodgson, Ralph, 1871-1962. (["Box 61, folder 1096-1097"])(ca. 1889-[1951])[Siegfried Sassoon]. https://collections.library.yale.edu/catalog/2007882.