Miyamoto Musashi, Yamamoto Tsunetomo, Inazo Nitobe (2010). “Honor: Samurai Philosophy of Life - The Essential Samurai Collection; The Book of Five Rings, Hagakure: The Way of the Samurai, Bushido: The Soul of Japan.”, p.16, Bottom of the Hill
Letter to Arthur Greeves on December 29, 1935. "They Stand Together: The Letters of C. S. Lewis to Arthur Greeves (1914-1963)". Book by C. S. Lewis, p. 477, 1979.