MLA

Speck, William A. (William Alfred), 1864-1928. ALS : Vienna, to Mr. Denis Brownell Murphy. Box 11, folder 410. 1835 May 7. https://collections.library.yale.edu/catalog/17266939.

APA, 6th edition

Speck, William A. (William Alfred), 1864-1928. (["Box 11, folder 410"])(1835 May 7)[ALS : Vienna, to Mr. Denis Brownell Murphy]. https://collections.library.yale.edu/catalog/17266939.