It was proposed by Branko Grünbaum to Ulf Rehmann that a a page with title "Polytope" is missing.
Quoting from an email by Grünbaum (dated 20 Apr 2012):
Polytope -- There is no entry dealing with that topic -- even though it started in the 19th century, and is a very important area of modern (pure as well as applied) mathematics.
Polytope. Encyclopedia of Mathematics. URL: http://www.encyclopediaofmath.org/index.php?title=Polytope&oldid=25364