[Letters: H. J. McMullen to R. E. Blair]
MLA
McMullen, H. J. [Letters: H. J. McMullen to R. E. Blair]. 1928. https://collections.library.yale.edu/catalog/10033797.
APA, 6th edition
McMullen, H. J. (1928). [Letters: H. J. McMullen to R. E. Blair] [Advertisements (AAT), Autographs, Blank forms, Clippings, correspondence (AAT), Letterheads, maps (AAT), periodicals (AAT), Prospectuses]. https://collections.library.yale.edu/catalog/10033797.