MLA

Loy, Mina (1882-1966). "First Costa Visit": draft. Box 1, folder 2. n.d.. https://collections.library.yale.edu/catalog/11173003.

APA, 6th edition

Loy, Mina (1882-1966). (["Box 1, folder 2"])(n.d.)["First Costa Visit": draft]. https://collections.library.yale.edu/catalog/11173003.