MLA

Bird, William, 1888-1963. Canto XIII. Box 2, folder 84. n.d.. https://collections.library.yale.edu/catalog/16164974.

APA, 6th edition

Bird, William, 1888-1963. (["Box 2, folder 84"])(n.d.)[Canto XIII]. https://collections.library.yale.edu/catalog/16164974.