Undated letter translated by Josiah Fisk and Jeff Nichols in "Composers on Music" (1997), p. 67; as quoted in "Gioacchino Rossini" by Luigi Rognoni, (p. 337), 1968.
Martín Prechtel (2013). “The Disobedience of the Daughter of the Sun: A Mayan Tale of Ecstasy, Time, and Finding One's True Form”, p.83, North Atlantic Books