MLA

Beinecke, Edwin J. (Edwin John), 1886-1970. "53". Box 34, folder 820. undated. https://collections.library.yale.edu/catalog/10971253.

APA, 6th edition

Beinecke, Edwin J. (Edwin John), 1886-1970. (["Box 34, folder 820"])(undated)["53"]. https://collections.library.yale.edu/catalog/10971253.