Cooper, B., & Wallace, C. (2001). Group selection and the evolution of altruism. University of Oxford.
Lua i Stíl Chicago (17ú heag.)Cooper, B., agus C. Wallace. Group Selection and the Evolution of Altruism. University of Oxford, 2001.
Lua MLA (9ú heag.)Cooper, B., agus C. Wallace. Group Selection and the Evolution of Altruism. University of Oxford, 2001.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.