MLA

Wolff, Helen, 1906-1994. Wolff, Alexander. Box 45, folder 1438. 1979, n.d.. https://collections.library.yale.edu/catalog/17269619.

APA, 6th edition

Wolff, Helen, 1906-1994. (["Box 45, folder 1438"])(1979, n.d.)[Wolff, Alexander]. https://collections.library.yale.edu/catalog/17269619.