MLA

Saarinen, Eero, 1910-1961. Knoll armchairs and settees. Box 83, folder 158. undated. https://collections.library.yale.edu/catalog/10017088.

APA, 6th edition

Saarinen, Eero, 1910-1961. (["Box 83, folder 158"])(undated)[Knoll armchairs and settees]. https://collections.library.yale.edu/catalog/10017088.