Bell, P. R. (1959). Darwin's biological work: Some aspects reconsidered. Cambridge University Press.
Lua i Stíl Chicago (17ú heag.)Bell, Peter R. Darwin's Biological Work: Some Aspects Reconsidered. Cambridge: Cambridge University Press, 1959.
Lua MLA (9ú heag.)Bell, Peter R. Darwin's Biological Work: Some Aspects Reconsidered. Cambridge University Press, 1959.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.