1. https://www.baseball-reference.com/leagues/AL/1908.shtml
2. Schwarz, Alan. “History of Rule Changes.” ESPN, February 4, 2020. Available at: http://a.espncdn.com/mlb/columns/schwarz_alan/1503763.html
3. https://www.baseball-reference.com/leagues/
4. Albert, Jim. “Sabermetrics: The Past, the Present, and the Future.” In Joseph Gallian, editor, Mathematics and Sports. Mathematical Association of America, 2010.
5. Costa, Gabriel, Michael Huber, and John Saccoman. Reasoning with Sabermetrics. McFarland and Company, 2012.