MLA

Saarinen, Eero, 1910-1961. Pevsner sculpture. Box 138, folder 277. undated. https://collections.library.yale.edu/catalog/10017580.

APA, 6th edition

Saarinen, Eero, 1910-1961. (["Box 138, folder 277"])(undated)[Pevsner sculpture]. https://collections.library.yale.edu/catalog/10017580.