MLA

Amichai, Yehuda, 1924-2000. Sexton, Anne. Box 10, folder 488. 1970 Feb 11. https://collections.library.yale.edu/catalog/16549134.

APA, 6th edition

Amichai, Yehuda, 1924-2000. (["Box 10, folder 488"])(1970 Feb 11)[Sexton, Anne]. https://collections.library.yale.edu/catalog/16549134.