Berra, T. M. (2009). Charles Darwin: The concise story of an extraordinary man. Johns Hopkins University Press.
Lua i Stíl Chicago (17ú heag.)Berra, Tim M. Charles Darwin: The Concise Story of an Extraordinary Man. Baltimore, Md.: Johns Hopkins University Press, 2009.
Lua MLA (9ú heag.)Berra, Tim M. Charles Darwin: The Concise Story of an Extraordinary Man. Johns Hopkins University Press, 2009.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.