MLA

Barrie, J. M. (James Matthew), 1860-1937. Llewelyn Davies, George. Box 9, folder 300-303. 1911–1915. https://collections.library.yale.edu/catalog/9998148.

APA, 6th edition

Barrie, J. M. (James Matthew), 1860-1937. (["Box 9, folder 300-303"])(1911–1915)[Llewelyn Davies, George]. https://collections.library.yale.edu/catalog/9998148.