MLA

Sergeant, Elizabeth Shepley, 1881-1965. Bergson, Henri. Box 1, folder 11. 1917. https://collections.library.yale.edu/catalog/17054220.

APA, 6th edition

Sergeant, Elizabeth Shepley, 1881-1965. (["Box 1, folder 11"])(1917)[Bergson, Henri]. https://collections.library.yale.edu/catalog/17054220.