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