MLA

Steinberg, Saul, 1914-1999. Untitled [A Magazine for People Who Read: Gas station along a desert highway]. Box 508 (Oversize), folder 7001. undated. https://collections.library.yale.edu/catalog/16855197.

APA, 6th edition

Steinberg, Saul, 1914-1999. (["Box 508 (Oversize), folder 7001"])(undated)[Untitled [A Magazine for People Who Read: Gas station along a desert highway]]. https://collections.library.yale.edu/catalog/16855197.