MLA

Robinson, R. B. (Robert B.), 1848-. R. B. Robinson letter, Charleston, West Virginia, to Benjamin F. Jones, New York, 1884 September 22 : manuscript. (File oversize). 1884 September 22.. https://collections.library.yale.edu/catalog/33189728.

APA, 6th edition

Robinson, R. B. (Robert B.), 1848-. (["(File oversize)"])(1884 September 22.)[R. B. Robinson letter, Charleston, West Virginia, to Benjamin F. Jones, New York, 1884 September 22 : manuscript]. https://collections.library.yale.edu/catalog/33189728.