Graham, b. (1998). The Secret of Happiness= Rahasia Kebahagiaan/ Billy Graham; Penerjemah, Wim Salampessy. Batam: interaksa.
Lua i Stíl Chicago (17ú heag.)Graham, billy. The Secret of Happiness= Rahasia Kebahagiaan/ Billy Graham; Penerjemah, Wim Salampessy. Batam: interaksa, 1998.
Lua MLA (8ú heag.)Graham, billy. The Secret of Happiness= Rahasia Kebahagiaan/ Billy Graham; Penerjemah, Wim Salampessy. Batam: interaksa, 1998.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.