MLA

Kirkup, James, 1918-2009. Play Strindberg, author's proofs. Box 107, folder 990. 1973. https://collections.library.yale.edu/catalog/16620273.

APA, 6th edition

Kirkup, James, 1918-2009. (["Box 107, folder 990"])(1973)[Play Strindberg, author's proofs]. https://collections.library.yale.edu/catalog/16620273.