(left to right): Henry Fairfield Osborn (1857-1935) and Leonard Darwin (1850-1943)

Chicago citation style
(left to right): Henry Fairfield Osborn (1857-1935) and Leonard Darwin (1850-1943). 1932. Retrieved from the Digital Public Library of America, http://collections.si.edu/search/results.htm?q=record_ID%3Asiris_arc_296678&repo=DPLA. (Accessed November 15, 2018.)
APA citation style
(1932) (left to right): Henry Fairfield Osborn (1857-1935) and Leonard Darwin (1850-1943). Retrieved from the Digital Public Library of America, http://collections.si.edu/search/results.htm?q=record_ID%3Asiris_arc_296678&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_296678&repo=DPLA>.
Note: These citations are programmatically generated and may be incomplete.