MLA

Opper, Frederick Burr, 1857-1937. Ten little tourists. 1890 September 17. https://collections.library.yale.edu/catalog/2057718.

APA, 6th edition

Opper, Frederick Burr, 1857-1937. (1890 September 17)[Ten little tourists]. https://collections.library.yale.edu/catalog/2057718.