Parker, S. (1992). Charles Darwin. Edinter.
Lua i Stíl Chicago (17ú heag.)Parker, Steve. Charles Darwin. Edinter, 1992.
Lua MLA (8ú heag.)Parker, Steve. Charles Darwin. Edinter, 1992.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.