MLA

Haas, Robert Bartlett (1916-2010). 21 additional items from Gertrude Stein Raffel concerning the Black Sparrow publication. Box 5. 1936-1985, undated. https://collections.library.yale.edu/catalog/17173431.

APA, 6th edition

Haas, Robert Bartlett (1916-2010). (["Box 5"])(1936-1985, undated)[21 additional items from Gertrude Stein Raffel concerning the Black Sparrow publication]. https://collections.library.yale.edu/catalog/17173431.