MLA

Josephson, Matthew, 1899-1978. Aragon, Louis. Box 1, folder 6-7. 1917-1979. https://collections.library.yale.edu/catalog/17091489.

APA, 6th edition

Josephson, Matthew, 1899-1978. (["Box 1, folder 6-7"])(1917-1979)[Aragon, Louis]. https://collections.library.yale.edu/catalog/17091489.