Wolfgang Amadeus Mozart, Friedrich Kerst, Henry Edward Krehbiel (1926). “Mozart: The Man and the Artist Revealed in His Own Words”, p.7, Courier Corporation
"Ringo was the secret ingredient and other revelations from Ron Howard’s Beatles movie" by Stephanie Merry, www.washingtonpost.com. September 16, 2016.
Ernest Bramah (2016). “ERNEST BRAMAH Ultimate Collection: 20+ Novels & Short Stories (Including Max Carrados Mysteries and Kai Lung Fantasy Stories): The Secret of the League, The Coin of Dionysius, The Game Played In the Dark, The Tilling Shaw Mystery, Kai Lung's Golden Hours, The Confession of Kai Lung, The Mirror of Kong Ho and many more”, p.527, e-artnow