MLA

Dreier, Katherine S. (Katherine Sophie), 1877-1952. Sixth International Congress for Drawing, Art Education, and Applied Arts (Prague). Box 62, folder 1681. 1928. https://collections.library.yale.edu/catalog/17047953.

APA, 6th edition

Dreier, Katherine S. (Katherine Sophie), 1877-1952. (["Box 62, folder 1681"])(1928)[Sixth International Congress for Drawing, Art Education, and Applied Arts (Prague)]. https://collections.library.yale.edu/catalog/17047953.