This page is critized as erronneous.
In an email to Ulf Rehmann, dated Apr 21, 2012, Branko Günbaum says:
The particular sentence I most strongly object to in the article "Polyhedron" is the statement that "Each isohedron can be realized so that all its faces are regular polygons." The simplest counterexamples are bipyramids on any basis with 6 of more sides. By the way, the statement before that, that "Isogons and isohedra are convex polygons ..." is also obvious nonsense, since the entry means to describe isogonal polyhedra. The separate entry Isogons and isohedra does not make this error.
Polyhedron. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Polyhedron&oldid=25366