Witherspoon, J., & Collins, V. L. (1912). Lectures on moral philosophy. Princeton university press.
Lua i Stíl Chicago (17ú heag.)Witherspoon, John, agus Varnum Lansing Collins. Lectures on Moral Philosophy. Princeton, N.J.: Princeton university press, 1912.
Lua MLA (8ú heag.)Witherspoon, John, agus Varnum Lansing Collins. Lectures on Moral Philosophy. Princeton university press, 1912.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.