Veech groups of flat structures on Riemann surfaces
  In this paper, we construct new examples of Veech groups by extending Schmithusen's method for calculating Veech groups of origamis to Veech groups of unramified finite coverings of regular 2n-gons. We calculate the Veech groups of certain Abelian coverings of regular 2n-gons by using an algebraic method. 
Yoshihiko Shinomiya
math.GT math.CV