This page is critized as anachronistic and needs urgent update.
In an email to Ulf Rehmann, dated Apr 20, 2012, Branko Günbaum says:
This entry could be mistaken as something from the Brückner book "Vielecke und Vielflache" published in 1900. No hint of any newer results of viewpoints.
Polygon. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Polygon&oldid=25457