MLA

Speck, William A. (William Alfred), 1864-1928. Fräulein Ulrike von Pogwisch, Weimar. Box 8, folder 253. 1824 Oct 29. https://collections.library.yale.edu/catalog/2005289.

APA, 6th edition

Speck, William A. (William Alfred), 1864-1928. (["Box 8, folder 253"])(1824 Oct 29)[Fräulein Ulrike von Pogwisch, Weimar]. https://collections.library.yale.edu/catalog/2005289.