MLA

Barrie, J. M. (James Matthew), 1860-1937. Typescript with autograph revisions. Box 44, folder 940. 1926 April 9. https://collections.library.yale.edu/catalog/32314624.

APA, 6th edition

Barrie, J. M. (James Matthew), 1860-1937. (["Box 44, folder 940"])(1926 April 9)[Typescript with autograph revisions]. https://collections.library.yale.edu/catalog/32314624.