MLA

McKay, Claude, 1890-1948. "Homing Swallows," typescript carbon. Box 12, folder 369. n.d.. https://collections.library.yale.edu/catalog/32268826.

APA, 6th edition

McKay, Claude, 1890-1948. (["Box 12, folder 369"])(n.d.)["Homing Swallows," typescript carbon]. https://collections.library.yale.edu/catalog/32268826.