MLA

Stieglitz, Alfred, 1864-1946. Schubart, Howard. Box 97, folder 1899-1901. 1952-53. https://collections.library.yale.edu/catalog/17414992.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 97, folder 1899-1901"])(1952-53)[Schubart, Howard]. https://collections.library.yale.edu/catalog/17414992.