MLA

Cortissoz, Royal, 1869-1948. "T" general. Box 10, folder 406-407. 1864-1942, n.d.. https://collections.library.yale.edu/catalog/17197466.

APA, 6th edition

Cortissoz, Royal, 1869-1948. (["Box 10, folder 406-407"])(1864-1942, n.d.)["T" general]. https://collections.library.yale.edu/catalog/17197466.