MLA

Speck, William A. (William Alfred), 1864-1928. LS : Weimar, to Johann Wolfgang Döbereiner. Box 9, folder 273. 1813 Mar 10. https://collections.library.yale.edu/catalog/2005303.

APA, 6th edition

Speck, William A. (William Alfred), 1864-1928. (["Box 9, folder 273"])(1813 Mar 10)[LS : Weimar, to Johann Wolfgang Döbereiner]. https://collections.library.yale.edu/catalog/2005303.