MLA

Speck, William A. (William Alfred), 1864-1928. ALS : Weimar, to Ludwig Friedrich von Froriep. Box 9, folder 276. 1824 Nov. https://collections.library.yale.edu/catalog/2005306.

APA, 6th edition

Speck, William A. (William Alfred), 1864-1928. (["Box 9, folder 276"])(1824 Nov)[ALS : Weimar, to Ludwig Friedrich von Froriep]. https://collections.library.yale.edu/catalog/2005306.