Partial table of contents: The Nine Regular Solids. The Regular Sponges, or Skew Polyhedra. Two Aspects of the Regular 24-Cell. The Densities of the Regular Polytopes I. The Densities of the Regular Polytopes II. The Densities of the Regular Polytopes III. A Challenging Definite Integral. Groups Whose Fundamental Regions Are Simplexes.

Discrete Groups Generated by Reflections. Finite Groups Generated by Reflections, and Their Subgroups Generated by Reflections. Orthogonal Trees. The Product of the Generators of a Finite Group Generated by Reflections. Extreme Forms. Regular and Semi-Regular Polytopes I. Regular and Semi-Regular Polytopes II. Regular and Semi-Regular Polytopes III.

Factor Groups of the Braid Group. Finite Groups Generated by Unitary Reflections. Index.