Graham, W. F. (1955). The secret of happiness: Jesus' teaching on happiness as expressed in the Beatitudes. Doubleday.
Cita Chicago (17th ed.)Graham, William Franklin. The Secret of Happiness: Jesus' Teaching on Happiness as Expressed in the Beatitudes. Garden City, N.Y: Doubleday, 1955.
Cita MLA (9th ed.)Graham, William Franklin. The Secret of Happiness: Jesus' Teaching on Happiness as Expressed in the Beatitudes. Doubleday, 1955.
Atenció: Aquestes cites poden no estar 100% correctes.