MLA

Chapman, J. G. (John Gadsby), 1808-1889, artist. David Crockett. [1850?]. https://collections.library.yale.edu/catalog/2015853.

APA, 6th edition

Chapman, J. G. (John Gadsby), 1808-1889, artist. ([1850?])[David Crockett]. https://collections.library.yale.edu/catalog/2015853.