1. S.L. Altmann, Induced Representations in Crystals and Molecules (Academic Press, London, 1977)
2. A.F. Beardon, The Geometry of Discrete Groups (Springer, Berlin, 1980)
3. L. Bellarosa, P.W. Fowler, E. Lijnen, M. Deza, Additional patterns in carbon allotropes: independent numbers and d-codes in Klein and related graphs. J. Chem. Inf. Comput. Sci. 44, 1314–1323 (2004)
4. P.J. Cameron (2006),
http://www.maths.qmul.ac.uk/~leonard/designtheory.org/library/encyc/topics/
5. C.M. Campbell, M.D.E. Conder, E.F. Robertson, Defining relations for Hurwitz groups. Math. J. 36, 363–370 (1990)