MLA

Carson, Rachel, 1907-1964. Heyerdahl, Thor. Box 12, folder 205. 1951. https://collections.library.yale.edu/catalog/32217982.

APA, 6th edition

Carson, Rachel, 1907-1964. (["Box 12, folder 205"])(1951)[Heyerdahl, Thor]. https://collections.library.yale.edu/catalog/32217982.