MLA

Morse, William R. (William Reginald), 1874-1939. William Morse to Mother from Yibin (Suifu), Chongqing (Chungking) summer bungalow. 1, folder 8. 1910 May. https://collections.library.yale.edu/catalog/33391256.

APA, 6th edition

Morse, William R. (William Reginald), 1874-1939. (["1, folder 8"])(1910 May)[William Morse to Mother from Yibin (Suifu), Chongqing (Chungking) summer bungalow]. https://collections.library.yale.edu/catalog/33391256.