MLA

Rudge, Olga, 1895-1996. Cantos. Box 13, folder 520. n.d.. https://collections.library.yale.edu/catalog/17082114.

APA, 6th edition

Rudge, Olga, 1895-1996. (["Box 13, folder 520"])(n.d.)[Cantos]. https://collections.library.yale.edu/catalog/17082114.