Marshall Goldsmith, Laurence S. Lyons, Sarah McArthur (2012). “Coaching for Leadership: Writings on Leadership from the World's Greatest Coaches”, p.49, John Wiley & Sons
Rudyard Kipling (2015). “Collected Works of Rudyard Kipling (Illustrated): 5 Novels & 350+ Short Stories, Poetry, Historical Military Works and Autobiographical Writings from one of the most popular writers in England, known for The Jungle Book, Kim, The Man Who Would Be King”, p.5236, e-artnow