MLA

Richardson, Dorothy M. (Dorothy Miller), 1873-1957. Kirkaldy, Peggy. Box 2, folder 18-28. 1932-45. https://collections.library.yale.edu/catalog/15237737.

APA, 6th edition

Richardson, Dorothy M. (Dorothy Miller), 1873-1957. (["Box 2, folder 18-28"])(1932-45)[Kirkaldy, Peggy]. https://collections.library.yale.edu/catalog/15237737.