# XMod : a GAP 4 package - References

[A1]
  M. Alp.
  GAP, crossed modules, cat1-groups: applications of computational group theory.
  Ph.D. thesis, University of Wales, Bangor, 1997.
[AW1]
  M. Alp and C. D. Wensley.
  Enumeration of cat1-groups of low order.
  Int. J. Algebra and Computation, 10:407--424, 2000.
[BH1]
  R. Brown and P. J. Higgins.
  On the connection between the second relative homotopy group and some related spaces.
  Proc. London Math. Soc., 36:193--212, 1978.
[B82]
  R. Brown.
  Higher-dimensional group theory.
  In R. Brown and T. L. Thickstun, editors, Low-dimensional topology, volume 48 of London Math. Soc. Lecture Note Series, pages 215--238. Cambridge University Press, 1982.
[BW1]
  R. Brown and C. D. Wensley.
  On finite induced crossed modules, and the homotopy 2-type of mapping cones.
  Theory and Applications of Categories, 1:54--71, 1995.
[BW2]
  R. Brown and C. D. Wensley.
  Computing crossed modules induced by an inclusion of a normal subgroup, with applications to homotopy 2-types.
  Theory and Applications of Categories, 2:3--16, 1996.
[BW3]
  R. Brown and C. D. Wensley.
  Computation and homotopical applications of induced crossed modules.
  J. Symbolic Computation, 35:59--72, 2003.
[E1]
  G. Ellis.
  Crossed modules and their higher dimensional analogues.
  Ph.D. thesis, University of Wales, Bangor, 1984.
[G1]
  N. D. Gilbert.
  Derivations, automorphisms and crossed modules.
  Comm. in Algebra, 18:2703--2734, 1990.
[L1]
  J. L. Loday.
  Spaces with finitely many non-trivial homotopy groups.
  J. App. Algebra, 24:179--202, 1982.
[M1]
  E. J. Moore.
  Graphs of Groups: Word Computations and Free Crossed Resolutions.
  Ph.D. thesis, University of Wales, Bangor, 2001.
[N2]
  K. J. Norrie.
  Crossed modules and analogues of group theorems.
  Ph.D. thesis, King's College, University of London, 1987.
[N1]
  K. J. Norrie.
  Actions and automorphisms of crossed modules.
  Bull. Soc. Math. France, 118:129--146, 1990.
[W2]
  J. H. C. Whitehead.
  On operators in relative homotopy groups.
  Ann. of Math., 49:610--640, 1948.
[W1]
  J. H. C. Whitehead.
  Combinatorial homotopy II.
  Bull. Amer. Math. Soc., 55:453--496, 1949.

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