MLA

Williams, Charles A., fl. 1857. [Autograph letter signed] 1857 March 22, Waterville, Le Sueur County, Minnesota Territory [to] Jonas Rawalt, Canton, Illinois. 1857 March 22. https://collections.library.yale.edu/catalog/2055738.

APA, 6th edition

Williams, Charles A., fl. 1857. (1857 March 22)[[Autograph letter signed] 1857 March 22, Waterville, Le Sueur County, Minnesota Territory [to] Jonas Rawalt, Canton, Illinois]. https://collections.library.yale.edu/catalog/2055738.