MLA

Dreier, Katherine S. (Katherine Sophie), 1877-1952. Cizek, Franz. Box 9, folder 234. 1926, n.d.. https://collections.library.yale.edu/catalog/16694408.

APA, 6th edition

Dreier, Katherine S. (Katherine Sophie), 1877-1952. (["Box 9, folder 234"])(1926, n.d.)[Cizek, Franz]. https://collections.library.yale.edu/catalog/16694408.