MLA

Carson, Rachel, 1907-1964. "Philosophy". Box 46, folder 883. n.d.. https://collections.library.yale.edu/catalog/17145180.

APA, 6th edition

Carson, Rachel, 1907-1964. (["Box 46, folder 883"])(n.d.)["Philosophy"]. https://collections.library.yale.edu/catalog/17145180.