MLA

Speck, William A. (William Alfred), 1864-1928. AL : Weimar, to Black Young & Young, booksellers, London. Box 9, folder 304. 1829 Nov 19. https://collections.library.yale.edu/catalog/2005346.

APA, 6th edition

Speck, William A. (William Alfred), 1864-1928. (["Box 9, folder 304"])(1829 Nov 19)[AL : Weimar, to Black Young & Young, booksellers, London]. https://collections.library.yale.edu/catalog/2005346.