MLA

Cortissoz, Royal, 1869-1948. Stieglitz, Alfred. Box 10, folder 404. 1925-32. https://collections.library.yale.edu/catalog/17197465.

APA, 6th edition

Cortissoz, Royal, 1869-1948. (["Box 10, folder 404"])(1925-32)[Stieglitz, Alfred]. https://collections.library.yale.edu/catalog/17197465.