MLA

Stein, Gertrude, 1874-1946. La Motte, Ellen. Box 113, folder 2348. 1913-36, n.d.. https://collections.library.yale.edu/catalog/16064729.

APA, 6th edition

Stein, Gertrude, 1874-1946. (["Box 113, folder 2348"])(1913-36, n.d.)[La Motte, Ellen]. https://collections.library.yale.edu/catalog/16064729.