Marden, O. S. (1913). Training for efficiency. Thomas Y. Crowell company.
Lua i Stíl Chicago (17ú heag.)Marden, Orison Swett. Training for Efficiency. New York: Thomas Y. Crowell company, 1913.
Lua MLA (8ú heag.)Marden, Orison Swett. Training for Efficiency. Thomas Y. Crowell company, 1913.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.