MLA

Dreier, Katherine S. (Katherine Sophie), 1877-1952. Doesburg, Alexander van. Box 11, folder 300. 1926, n.d.. https://collections.library.yale.edu/catalog/11040275.

APA, 6th edition

Dreier, Katherine S. (Katherine Sophie), 1877-1952. (["Box 11, folder 300"])(1926, n.d.)[Doesburg, Alexander van]. https://collections.library.yale.edu/catalog/11040275.