MLA

Dreier, Katherine S. (Katherine Sophie), 1877-1952. Nichols, Rose Standish. Box 27, folder 784. 1927 Oct 9. https://collections.library.yale.edu/catalog/16694424.

APA, 6th edition

Dreier, Katherine S. (Katherine Sophie), 1877-1952. (["Box 27, folder 784"])(1927 Oct 9)[Nichols, Rose Standish]. https://collections.library.yale.edu/catalog/16694424.