Leff, G. (1969). History and social theory. University of Alabama Press.
Lua i Stíl Chicago (17ú heag.)Leff, Gordon. History and Social Theory. University, Ala: University of Alabama Press, 1969.
Lua MLA (9ú heag.)Leff, Gordon. History and Social Theory. University of Alabama Press, 1969.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.