MLA

Morse, William R. (William Reginald), 1874-1939. William Morse and Anne Morse to Marjorie Morse from Leshan (Kiating), Nanking, Chengdu (Chengtu), Beh Liu Tin, Miao country. 4, folder 85. 1936 April-July. https://collections.library.yale.edu/catalog/33391103.

APA, 6th edition

Morse, William R. (William Reginald), 1874-1939. (["4, folder 85"])(1936 April-July)[William Morse and Anne Morse to Marjorie Morse from Leshan (Kiating), Nanking, Chengdu (Chengtu), Beh Liu Tin, Miao country]. https://collections.library.yale.edu/catalog/33391103.