MLA

Dreier, Katherine S. (Katherine Sophie), 1877-1952. Kandinsky, Wassily. Box 105, folder 2561-2569. 1926-50, n.d.. https://collections.library.yale.edu/catalog/2014499.

APA, 6th edition

Dreier, Katherine S. (Katherine Sophie), 1877-1952. (["Box 105, folder 2561-2569"])(1926-50, n.d.)[Kandinsky, Wassily]. https://collections.library.yale.edu/catalog/2014499.