MLA

Henri, Robert, 1865-1929. Correspondence. Box 13, folder 321-322. 1890 Dec. https://collections.library.yale.edu/catalog/17029586.

APA, 6th edition

Henri, Robert, 1865-1929. (["Box 13, folder 321-322"])(1890 Dec)[Correspondence]. https://collections.library.yale.edu/catalog/17029586.