MLA

Loy, Mina (1882-1966). "Marble". Box 5, folder 143. n.d.. https://collections.library.yale.edu/catalog/11700604.

APA, 6th edition

Loy, Mina (1882-1966). (["Box 5, folder 143"])(n.d.)["Marble"]. https://collections.library.yale.edu/catalog/11700604.