Invariant Meromorphic Functions on the Wallpaper Groups
  We construct the meromorphic functions invariant under the action of the sense-preserving wallpaper groups on the complex plane. We discuss possible generalisa-tions of this to the general wallpaper groups. This provides the answer to a question posed on StackExchange regarding the possible symmetries of elliptic functions. 
Richard Chapling
math.CA math.CV math.GR