MLA

McKay, Claude, 1890-1948. Jackman, Harold. Box 4, folder 103-109. 1927-44, n.d.. https://collections.library.yale.edu/catalog/32464243.

APA, 6th edition

McKay, Claude, 1890-1948. (["Box 4, folder 103-109"])(1927-44, n.d.)[Jackman, Harold]. https://collections.library.yale.edu/catalog/32464243.