1. E. Artin,Geometric Algebra, Interscience, New York, 1957.
2. J. Casey,A sequel to the First Six Books of the Elements of Euclid, 6th. ed., Longmans, London, 1892.
3. H. S. M. Coxeter,Regular Polytopes, Methuen, London, 1948.
4. H. S. M. Coxeter,Introduction to Geometry, Wiley, New York, 1961.
5. L. R. Ford,Automorphic Functions, McGraw Hill, New York, 1929.