“…Then, for each 3 ≤ n ≤ 22, we may choose q 0 as follows: Verifying which of these (finitely many) pairs (n, q) satisfy φ(N ) n | 2| Out(S)| (see the Appendix for the complete set of computations), we determine that S = PSL n (q) can occur as a composition factor of a quadratic rational group only if (n, q) ∈ {(2, 4), (2,5), (2, 7), (2,8), (2,9), (2,11), (2,16), (2,19), (2,23), (2,27), (2,31), (3,2), (3,3), (3,4), (3,7), (3,16) is to occur as a composition factor of a quadratic rational group, it must be the case…”