  
  
  [1XReferences[0X
  
  [[20XEGN[15X]    [16XEick,    B.,    G\"ahler,    F.    and   Nickel,   W.[15X,   [17Xcryst[15X,
  \URL{http://www.gap-system.org/Packages/cryst.html}
  
  [[20XEll[15X] [16XEllis, G.[15X, [17XHAP[15X, \URL{http://hamilton.nuigalway.ie/Hap/www/}
  
  
  
  -------------------------------------------------------
