MLA

Carson, Rachel, 1907-1964. Conservation: general. Box 32, folder 562. 1957, n.d.. https://collections.library.yale.edu/catalog/17145161.

APA, 6th edition

Carson, Rachel, 1907-1964. (["Box 32, folder 562"])(1957, n.d.)[Conservation: general]. https://collections.library.yale.edu/catalog/17145161.