MLA

McKay, Claude, 1890-1948. Locke, Alain LeRoy. Box 5, folder 138. 1927-30. https://collections.library.yale.edu/catalog/16742352.

APA, 6th edition

McKay, Claude, 1890-1948. (["Box 5, folder 138"])(1927-30)[Locke, Alain LeRoy]. https://collections.library.yale.edu/catalog/16742352.