MLA

Saarinen, Eero, 1910-1961. Model. Box 59, folder 42. undated. https://collections.library.yale.edu/catalog/10016945.

APA, 6th edition

Saarinen, Eero, 1910-1961. (["Box 59, folder 42"])(undated)[Model]. https://collections.library.yale.edu/catalog/10016945.