1. The orbits of the product of two permutations;Brenner, J. L.;European J. Combin.,1983
2. On the automorphism group of a planar hypermap;Cori, Robert;European J. Combin.,1981
3. Ergebnisse der Mathematik und ihrer Grenzgebiete, Band 89;Lyndon, Roger C.,1977
4. Homology of hypermaps;Machì, Antonio;J. London Math. Soc. (2),1985
5. Pure and Applied Mathematics, Vol. 61;Magnus, Wilhelm,1974