MLA

Carson, Rachel, 1907-1964. Holograph. Box 93, folder 1635. n.d.. https://collections.library.yale.edu/catalog/2004853.

APA, 6th edition

Carson, Rachel, 1907-1964. (["Box 93, folder 1635"])(n.d.)[Holograph]. https://collections.library.yale.edu/catalog/2004853.