MLA

[Sketchbook]. 0AD. https://collections.library.yale.edu/catalog/11219803.

APA, 6th edition

[Sketchbook]. (0 C.E.). [Graphite drawings--United States--20th century.--gmgpc, Ink drawings.--gmgpc, Portrait drawings, Sketches--United States--20th century.--aat]. https://collections.library.yale.edu/catalog/11219803.