MLA

Wescott, Glenway, 1901-1987. Burns, John Horne. Box 40, folder 544. 1949 Jan 30. https://collections.library.yale.edu/catalog/17065001.

APA, 6th edition

Wescott, Glenway, 1901-1987. (["Box 40, folder 544"])(1949 Jan 30)[Burns, John Horne]. https://collections.library.yale.edu/catalog/17065001.