MLA

Tunnard, Christopher, 1910-1979. Tunnard family photographs. Box 42, folder 699. undated. https://collections.library.yale.edu/catalog/10014268.

APA, 6th edition

Tunnard, Christopher, 1910-1979. (["Box 42, folder 699"])(undated)[Tunnard family photographs]. https://collections.library.yale.edu/catalog/10014268.