MLA

Barrie, J. M. (James Matthew), 1860-1937. Letters. Box 1, folder 19-24. 1919–1924. https://collections.library.yale.edu/catalog/32309702.

APA, 6th edition

Barrie, J. M. (James Matthew), 1860-1937. (["Box 1, folder 19-24"])(1919–1924)[Letters]. https://collections.library.yale.edu/catalog/32309702.