International Journal of Game Theory. 44 (3): 761–767. doi:10.1007/s00182-014-0453-7. S2CID 31972497. ↑ Gourion, Daniel (2021-12-16), An upper bound for the number of chess diagrams without promotion, arXiv:2112.09386, retrieved 2021-12-18 ↑ "How many chess games are possible?"