MLA

Dobson, Silvia, 1908-. Copies of letters from HD to Dobson, letters 1-42, File I, pages 1-125, 1934-May 1935. Box 6, folder 82. undated. https://collections.library.yale.edu/catalog/32190533.

APA, 6th edition

Dobson, Silvia, 1908-. (["Box 6, folder 82"])(undated)[Copies of letters from HD to Dobson, letters 1-42, File I, pages 1-125, 1934-May 1935]. https://collections.library.yale.edu/catalog/32190533.