MLA

Stenzel, Franz (1906-1998). "From Pt. Boneta - Entrance San Francisco Bay." Watercolor, 23.6 x 30.7 cm.. Box 2, folder 23. n.d.. https://collections.library.yale.edu/catalog/10691152.

APA, 6th edition

Stenzel, Franz (1906-1998). (["Box 2, folder 23"])(n.d.)["From Pt. Boneta - Entrance San Francisco Bay." Watercolor, 23.6 x 30.7 cm.]. https://collections.library.yale.edu/catalog/10691152.