MLA

Henri, Robert, 1865-1929. Correspondence. Box 13, folder 318-319. 1890 Oct. https://collections.library.yale.edu/catalog/17029584.

APA, 6th edition

Henri, Robert, 1865-1929. (["Box 13, folder 318-319"])(1890 Oct)[Correspondence]. https://collections.library.yale.edu/catalog/17029584.