1.75 (1965)

They are classified for every $p$ mod the classification of finite simple groups (CFSG) (V. V. Belyaev, in: Investigations in Group Theory, Sverdlovsk, UNC AN SSSR, 1984, 39–50 (Russian); A. V. Borovik, Siberian Math. J., 24, no. 6 (1983), 843–851; B. Hartley, G. Shute, Quart. J. Math. (2), 35 (1984), 49–71; S. Thomas, Arch. Math., 41 (1983), 103–116). For $p > 2$ there is a proof without using the CFSG (A. V. Borovik, Siberian Math. J., 25, no. 2 (1984), 221–235). For all $p$, without using CFSG, the classification also follows from the paper (M. J. Larsen, R. Pink, J. Amer. Math. Soc., 24 (2011), 1105–1158) also known as a preprint of 1998.