Untitled [Envelope with seven faux stamps in purple and blue ink]
MLA
Steinberg, Saul, 1914-1999. Untitled [Envelope with seven faux stamps in purple and blue ink]. Box 76, folder 1449. undated. https://collections.library.yale.edu/catalog/16855948.
APA, 6th edition
Steinberg, Saul, 1914-1999. (["Box 76, folder 1449"])(undated)[Untitled [Envelope with seven faux stamps in purple and blue ink]]. https://collections.library.yale.edu/catalog/16855948.