Characterization of the Linear Groups PSL(2, p)

Let G be a finite group and pi(e)(G) be the set of element orders of G. Let k epsilon pi(e)(G) and m k be the number of elements of order k in G. Set nse(G):={m(k) vertical bar k epsilon(G)}. In this paper, it is proved if G is a group with the following properties, then G congruent to PSL(2, p). 1) p is the prime divisor of order G but p(2) not divide order of G. 2) nse(G)= nse(PSL(2, p)).