MLA

Barrie, J. M. (James Matthew), 1860-1937. Autograph manuscript. Box 29, folder 783-786. undated. https://collections.library.yale.edu/catalog/17462846.

APA, 6th edition

Barrie, J. M. (James Matthew), 1860-1937. (["Box 29, folder 783-786"])(undated)[Autograph manuscript]. https://collections.library.yale.edu/catalog/17462846.