MLA

Barrie, J. M. (James Matthew), 1860-1937. Notebook 6. Box 22, folder 728. 1885-1888?. https://collections.library.yale.edu/catalog/32312779.

APA, 6th edition

Barrie, J. M. (James Matthew), 1860-1937. (["Box 22, folder 728"])(1885-1888?)[Notebook 6]. https://collections.library.yale.edu/catalog/32312779.