MLA

Stieglitz, Alfred, 1864-1946. Letters. Box 64, folder 1452-1458. 1929 Apr-Jun. https://collections.library.yale.edu/catalog/2039887.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 64, folder 1452-1458"])(1929 Apr-Jun)[Letters]. https://collections.library.yale.edu/catalog/2039887.