“…In [12] and [18], finite groups with the same prime graph as PSL(2, q), where q is not prime, are determined. It is proved that simple groups F 4 (q), where q = 2 n > 2 (see [10]) and 2 F 4 (q) (see [1]) are quasirecognizable by prime graph. Also in [9], it is proved that if p is a prime number which is not a Mersenne or a Fermat prime and p = 11, 13, 19, and Γ(G) = Γ(PGL(2, p)), then G has a unique nonabelian composition factor which is isomorphic to PSL(2, p); while if p = 13, then G has a unique nonabelian composition factor which is isomorphic to PSL (2,13) or PSL (2,27).…”