MLA

Dreier, Katherine S. (Katherine Sophie), 1877-1952. Villon, Jacques; Villon, Gaby. Box 35, folder 1048-1049. 1923-1951, undated. https://collections.library.yale.edu/catalog/2040525.

APA, 6th edition

Dreier, Katherine S. (Katherine Sophie), 1877-1952. (["Box 35, folder 1048-1049"])(1923-1951, undated)[Villon, Jacques; Villon, Gaby]. https://collections.library.yale.edu/catalog/2040525.