  
  
  [1XReferences[101X
  
  [[20XBBN+78[120X] [16XBrown, H., Bülow, R., Neubüser, J., Wondratschek, H. and Zassenhaus, H.[116X, [17XCrystallographic Groups of Four-Dimensional
  Space[117X, John Wiley, New York (1978).
  
  [[20XHah95[120X]  ([1m[31mHahn,  T.[15X,  Ed.),  [17XInternational  Tables  for Crystallography, Volume A, Space-group Symmetry[117X, Kluwer, 4th edition,
  Dordrecht (1995).
  
  [[20XNPW81[120X]  [16XNeubüser,  J.,  Plesken,  W.  and  Wondratschek, H.[116X, [17XAn emendatory discursion on defining crystal systems[117X, [18XMatch[118X, [19X10[119X
  (1981), 77--96.
  
  
  
  [32X
