MLA

Dreier, Katherine S. (Katherine Sophie), 1877-1952. Picasso, Pablo. Box 111, folder 2675-2677. 1913-51, n.d.. https://collections.library.yale.edu/catalog/2016747.

APA, 6th edition

Dreier, Katherine S. (Katherine Sophie), 1877-1952. (["Box 111, folder 2675-2677"])(1913-51, n.d.)[Picasso, Pablo]. https://collections.library.yale.edu/catalog/2016747.