(left to right): Katharine Pember Darwin (1901-1986), Charles Galton Darwin (1887-1962), and Watson Davis (1896-1967)

Chicago citation style
(left to right): Katharine Pember Darwin (1901-1986), Charles Galton Darwin (1887-1962), and Watson Davis (1896-1967). December 1941. Retrieved from the Digital Public Library of America, http://collections.si.edu/search/results.htm?q=record_ID%3Asiris_arc_296674&repo=DPLA. (Accessed November 19, 2018.)
APA citation style
(December 1941) (left to right): Katharine Pember Darwin (1901-1986), Charles Galton Darwin (1887-1962), and Watson Davis (1896-1967). Retrieved from the Digital Public Library of America, http://collections.si.edu/search/results.htm?q=record_ID%3Asiris_arc_296674&repo=DPLA
MLA citation style
Retrieved from the Digital Public Library of America <http://collections.si.edu/search/results.htm?q=record_ID%3Asiris_arc_296674&repo=DPLA>.
Note: These citations are programmatically generated and may be incomplete.