  
  
  [1XReferences[101X
  
  [[20XOPS98[120X]   [16XOpgenorth,  J.,  Plesken,  W.  and  Schulz,  T.[116X,  [17XCrystallographic
  Algorithms and Tables[117X, [18XActa Cryst. A[118X, [19X54[119X (1998), 517--531.
  
  
  
  [32X
