MLA

Beinecke, Edwin J. (Edwin John), 1886-1970. Stevenson, Robert Alan Mowbray (5663-5740). Box 20, folder 527. 1868-1893. https://collections.library.yale.edu/catalog/10257615.

APA, 6th edition

Beinecke, Edwin J. (Edwin John), 1886-1970. (["Box 20, folder 527"])(1868-1893)[Stevenson, Robert Alan Mowbray (5663-5740)]. https://collections.library.yale.edu/catalog/10257615.