MLA

Loy, Mina (1882-1966). "Summer Night in a Florentine Slum". Box 5, folder 123. n.d.. https://collections.library.yale.edu/catalog/11700583.

APA, 6th edition

Loy, Mina (1882-1966). (["Box 5, folder 123"])(n.d.)["Summer Night in a Florentine Slum"]. https://collections.library.yale.edu/catalog/11700583.