MLA

Stieglitz, Alfred, 1864-1946. Rubenstein, Meridel. Box 212, folder 3727. 1974-75. https://collections.library.yale.edu/catalog/32416676.

APA, 6th edition

Stieglitz, Alfred, 1864-1946. (["Box 212, folder 3727"])(1974-75)[Rubenstein, Meridel]. https://collections.library.yale.edu/catalog/32416676.