MLA

Speck, William A. (William Alfred), 1864-1928. ALS : Vienna, to Prof. Friedrich Wilhelm Riemer. Box 1, folder 13. 1832 Feb 15. https://collections.library.yale.edu/catalog/15808638.

APA, 6th edition

Speck, William A. (William Alfred), 1864-1928. (["Box 1, folder 13"])(1832 Feb 15)[ALS : Vienna, to Prof. Friedrich Wilhelm Riemer]. https://collections.library.yale.edu/catalog/15808638.