MLA

Dreier, Katherine S. (Katherine Sophie), 1877-1952. Albers, Josef. Box 1, folder 19-20. 1934-50. https://collections.library.yale.edu/catalog/32202325.

APA, 6th edition

Dreier, Katherine S. (Katherine Sophie), 1877-1952. (["Box 1, folder 19-20"])(1934-50)[Albers, Josef]. https://collections.library.yale.edu/catalog/32202325.