Beckwith, H. Selling the Invisible. Warner Books.
Lua i Stíl Chicago (17ú heag.)Beckwith, Harry. Selling the Invisible. Warner Books.
Lua MLA (9ú heag.)Beckwith, Harry. Selling the Invisible. Warner Books.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.