Heilbroner, R. L. (1974). An inquiry into the human prospect. W.W. Norton.
Lua i Stíl Chicago (17ú heag.)Heilbroner, Robert L. An Inquiry into the Human Prospect. New York: W.W. Norton, 1974.
Lua MLA (9ú heag.)Heilbroner, Robert L. An Inquiry into the Human Prospect. W.W. Norton, 1974.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.