MLA

Carson, Rachel, 1907-1964. Aviation spraying. Box 30, folder 526. n.d.. https://collections.library.yale.edu/catalog/17145160.

APA, 6th edition

Carson, Rachel, 1907-1964. (["Box 30, folder 526"])(n.d.)[Aviation spraying]. https://collections.library.yale.edu/catalog/17145160.