Freakonomics by Steven D. Levitt and Stephen J. Dubner: “There is a lot to know about sumo, and quite a bit can be found in these books: Mina Hall, The Big Book of Sumo (Berkeley, Calif.: Stonebridge Press, 1997); Keisuke Itai, Nakabon (Tokyo: Shogakkan Press, 2000); and Onaruto, Yaocho (Tokyo: Line Books, 2000).”