MLA

Barrie, J. M. (James Matthew), 1860-1937. Pinero, Arthur Wing. Box 13, folder 425. 1903?-1933. https://collections.library.yale.edu/catalog/32312599.

APA, 6th edition

Barrie, J. M. (James Matthew), 1860-1937. (["Box 13, folder 425"])(1903?-1933)[Pinero, Arthur Wing]. https://collections.library.yale.edu/catalog/32312599.