MLA

Haas, Robert Bartlett (1916-2010). 23 autograph letters signed and 2 autograph postcards signed from Alice B. Toklas to Haas, with original envelopes. Box 3. 1946-1955. https://collections.library.yale.edu/catalog/17173421.

APA, 6th edition

Haas, Robert Bartlett (1916-2010). (["Box 3"])(1946-1955)[23 autograph letters signed and 2 autograph postcards signed from Alice B. Toklas to Haas, with original envelopes]. https://collections.library.yale.edu/catalog/17173421.