MLA

Saarinen, Eero, 1910-1961. Furniture models. Box 138, folder 271. undated. https://collections.library.yale.edu/catalog/10017454.

APA, 6th edition

Saarinen, Eero, 1910-1961. (["Box 138, folder 271"])(undated)[Furniture models]. https://collections.library.yale.edu/catalog/10017454.