MLA

Morse, William R. (William Reginald), 1874-1939. William Morse and Anne Morse to Marjorie Morse from Chengdu (Chengtu). 4, folder 83. 1936 January-March. https://collections.library.yale.edu/catalog/33391066.

APA, 6th edition

Morse, William R. (William Reginald), 1874-1939. (["4, folder 83"])(1936 January-March)[William Morse and Anne Morse to Marjorie Morse from Chengdu (Chengtu)]. https://collections.library.yale.edu/catalog/33391066.