Self-embeddings of Hamming Steiner triple systems of small order and APN   permutations
  The classification, up to isomorphism, of all self-embedding monomial power permutations of Hamming Steiner triple systems of order n=2^m-1 for small m, m < 23, is given. As far as we know, for m in {5,7,11,13,17,19}, all given self-embeddings in closed surfaces are new. Moreover, they are cyclic for all m and nonorientable at least for all m < 21. For any non prime m, the nonexistence of such self-embeddings in a closed surface is proven. 
J. Rif\`a, F. I. Solov'eva, M. Villanueva
cs.IT math.IT