MLA

Barrie, J. M. (James Matthew), 1860-1937. Autograph manuscript, signed and dated. Box 39, folder 879. 1913 January 28. https://collections.library.yale.edu/catalog/32313482.

APA, 6th edition

Barrie, J. M. (James Matthew), 1860-1937. (["Box 39, folder 879"])(1913 January 28)[Autograph manuscript, signed and dated]. https://collections.library.yale.edu/catalog/32313482.