MLA

Steinberg, Saul, 1914-1999. Untitled [Vase with flowers]. Box 459, folder 6377. undated. https://collections.library.yale.edu/catalog/16851501.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 459, folder 6377"])(undated)[Untitled [Vase with flowers]]. https://collections.library.yale.edu/catalog/16851501.