On the growth rates of cofinite 3-dimensional hyperbolic Coxeter groups   whose dihedral angles are of the form $\frac{\pi}{m}$ for $m=2,3,4,5,6$
  We study arithmetic properties of the growth rates of cofinite 3-dimensional hyperbolic Coxeter groups whose dihedral angles are of the form $\frac{\pi}{m}$ for $m=2,3,4,5,6$ and show that the growth rates are always Perron numbers. 
Tomoshige Yukita
math.GT