Greg, P. (1883). Without God: Negative science and natural ethics. Hurst and Blackett.
Lua i Stíl Chicago (17ú heag.)Greg, Percy. Without God: Negative Science and Natural Ethics. London: Hurst and Blackett, 1883.
Lua MLA (8ú heag.)Greg, Percy. Without God: Negative Science and Natural Ethics. Hurst and Blackett, 1883.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.