Reflection groups
Some (mostly on-line) resources
Books:
J.E. Humphreys,
Reflection Groups and Coxeter Groups
H.S.M. Coxeter,
Regular polytopes
, New York: Pitman, 1948 (
library link
).
M.W. Davis,
Geometry and Topology of Coxeter groups
.
Lecture notes:
A.M. Cohen,
Coxeter groups
.
D. Speyer,
Coxeter groups
course webpage.
Some papers:
E. Vinberg,
Hyperbolic reflection groups
I.V. Dolgachev,
Reflection groups in algebraic geometry
.
S. Fomin, N. Reading,
Root systems and generalized assosiahedra
Webpages:
A. Felikson,
Hyperbolic Coxeter polytopes
, webpage.