MLA

Stein, Gertrude, 1874-1946. Imbs, Bravig. Box 152, folder 3703-3704. ca. 1928. https://collections.library.yale.edu/catalog/2009743.

APA, 6th edition

Stein, Gertrude, 1874-1946. (["Box 152, folder 3703-3704"])(ca. 1928)[Imbs, Bravig]. https://collections.library.yale.edu/catalog/2009743.