MLA

Matthiessen, F. O. (Francis Otto), 1902-1950. National Guardian. Box 13. 1948. https://collections.library.yale.edu/catalog/32240067.

APA, 6th edition

Matthiessen, F. O. (Francis Otto), 1902-1950. (["Box 13"])(1948)[National Guardian]. https://collections.library.yale.edu/catalog/32240067.