  
  
  [1XReferences[101X
  
  [[20XAus60[120X]  [16XAuslander,  L.[116X,  [17XBieberbach's  theorem on space groups and discrete
  uniform subgroups of Lie groups[117X, [18XAnn. of Math.[118X, [19X71[119X, 3 (1960), 579--590.
  
  [[20XBro82[120X] [16XBrown, K. S.[116X, [17XCohomology of Groups[117X, Springer-Verlag, New York, Grad.
  Texts in Math., [19X87[119X (1982).
  
  [[20XDE02[120X]  [16XDekimpe,  K. and Eick, B.[116X, [17XComputational aspects of group extensions
  and their applications in topology[117X, [18XExp. Math.[118X, [19X11[119X, 2 (2002), 183--200.
  
  [[20XDE03[120X]  [16XDekimpe,  K. and Eick, B.[116X, [17XComputations with almost-crystallographic
  groups[117X, in Groups St. Andrews 2001 in Oxford. Vol. I, Cambridge Univ. Press,
  Cambridge, London Math. Soc. Lecture Note Ser., [19X304[119X (2003), 110--119.
  
  [[20XDek96[120X]   [16XDekimpe,  K.[116X,  [17XAlmost-Bieberbach  Groups:  Affine  and  Polynomial
  Structures[117X,  Springer-Verlag, Heidelberg, Lecture Notes in Mathematics, [19X1639[119X
  (1996).
  
  [[20XDM01[120X] [16XDescheemaeker, A. and Malfait, W.[116X, [17XP-localization of Relative Groups[117X,
  [18XJournal of Pure and Applied Algebra[118X, [19X159[119X, 1 (2001).
  
  [[20XLee88[120X]  [16XLee,  K.  B.[116X, [17XThere are only finitely many infra-nilmanifolds under
  each nilmanifold[117X, [18XQuart. J. Math. Oxford[118X, [19X39[119X, 2 (1988), 61--66.
  
  
  
  [32X
