MLA

Albertson, Ralph, 1866-1951. Albertson, Ralph. Box 10, folder 1. 1890-1950, undated. https://collections.library.yale.edu/catalog/10020219.

APA, 6th edition

Albertson, Ralph, 1866-1951. (["Box 10, folder 1"])(1890-1950, undated)[Albertson, Ralph]. https://collections.library.yale.edu/catalog/10020219.