References
  
  [BIRS14] Bruns, W., Ichim, B., Römer, T. and Söger, C., Normaliz, a tool for
  computations  in  affine  monoids, vector configurations, lattice polytopes,
  and        rational        cones,        Version        3.1.0        (2014),
  https://www.normaliz.uni-osnabrueck.de.