MLA

Stieglitz, Alfred, 1864-1946. Letters. Box 62, folder 1429-1430. 1922 May. https://collections.library.yale.edu/catalog/2039792.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 62, folder 1429-1430"])(1922 May)[Letters]. https://collections.library.yale.edu/catalog/2039792.