@manual{ AutoDoc,
  author =           {Gutsche, S. and Horn, M.},
  title =            {{AutoDoc  \texttt{\symbol{45}}  Generate documentation
                      from GAP source code (Version 2017.09.15)}},
  year =             {2017},
  note =             {GAP                   package,                   \href
                      {https://github.com/gap-packages/AutoDoc}
                      {\texttt{https://github.com/}\discretionary
                      {}{}{}\texttt{gap\texttt{\symbol{45}}packages/}\discretionary
                      {}{}{}\texttt{AutoDoc}}},
  printedkey =       {GH17}
}
@manual{ GAPDoc,
  author =           {L{\"u}beck, F. and Neunh{\"o}ffer, M.},
  title =            {{GAPDoc (version 1.6)}},
  organization =     {RWTH Aachen},
  year =             {2017},
  note =             {GAP                   package,                   \href
                      {https://www.math.rwth-aachen.de/~Frank.Luebeck/GAPDoc/index.html}
                      {\texttt{https://www.math.rwth\texttt{\symbol{45}}aachen.de/}\discretionary
                      {}{}{}\texttt{\texttt{\symbol{126}}Frank.Luebeck/}\discretionary
                      {}{}{}\texttt{GAPDoc/}\discretionary
                      {}{}{}\texttt{index.html}}},
  printedkey =       {LN17}
}
@manual{ GitHubPagesForGAP,
  author =           {Horn, M.},
  title =            {{GitHubPagesForGAP  \texttt{\symbol{45}}  Template for
                      easily using GitHub Pages within GAP packages (Version
                      0.2)}},
  year =             {2017},
  note =             {GAP                   package,                   \href
                      {https://gap-system.github.io/GitHubPagesForGAP/}
                      {\texttt{https://gap\texttt{\symbol{45}}system.github.io/}\discretionary
                      {}{}{}\texttt{GitHubPagesForGAP/}}},
  printedkey =       {Hor17}
}
@phdthesis{ A1,
  author =           {Alp, M.},
  title =            {GAP,  crossed modules, cat1\texttt{\symbol{45}}groups:
                      applications of computational group theory},
  school =           {University of Wales, Bangor},
  year =             {1997},
  printedkey =       {Alp97}
}
@article{ AW1,
  author =           {Alp, M. and Wensley, C. D.},
  title =            {Enumeration  of  cat1\texttt{\symbol{45}}groups of low
                      order},
  journal =          {Int. J. Algebra and Computation},
  volume =           {10},
  year =             {2000},
  pages =            {407\texttt{\symbol{45}}\texttt{\symbol{45}}424},
  printedkey =       {AW00}
}
@article{ AW2,
  author =           {Alp, M. and Wensley, C. D.},
  title =            {Automorphisms  and homotopies of groupoids and crossed
                      modules},
  journal =          {Applied Categorical Structures},
  volume =           {18},
  year =             {2010},
  pages =            {473\texttt{\symbol{45}}495},
  printedkey =       {AW10}
}
@article{ AOW,
  author =           {Arvasi, Z. and Odabas, A. and Wensley, C. D.},
  title =            {Computing  3\texttt{\symbol{45}}Dimensional  Groups  :
                      Crossed Squares and Cat2\texttt{\symbol{45}}groups},
  journal =          {J. Symbolic Computation},
  volume =           {114},
  year =             {2023},
  pages =            {267\texttt{\symbol{45}}281},
  printedkey =       {AOW23}
}
@inproceedings{ B82,
  author =           {Brown, R.},
  editor =           {Brown, R. and Thickstun, T. L.},
  booktitle =        {Low\texttt{\symbol{45}}dimensional topology},
  title =            {Higher\texttt{\symbol{45}}dimensional group theory},
  publisher =        {Cambridge University Press},
  series =           {London Math. Soc. Lecture Note Series},
  volume =           {48},
  year =             {1982},
  pages =            {215\texttt{\symbol{45}}\texttt{\symbol{45}}238},
  printedkey =       {Bro82}
}
@article{ B18,
  author =           {Brown, R.},
  title =            {Crossed       modules,      and      the      homotopy
                      2\texttt{\symbol{45}}type of a free loop space},
  journal =          {arXiv:1003.5617 [math.AT]},
  year =             {2018},
  pages =            {1\texttt{\symbol{45}}\texttt{\symbol{45}}11},
  printedkey =       {Bro18}
}
@article{ BH1,
  author =           {Brown, R. and Higgins, P. J.},
  title =            {On the connection between the second relative homotopy
                      group and some related spaces},
  journal =          {Proc. London Math. Soc.},
  volume =           {36},
  year =             {1978},
  pages =            {193\texttt{\symbol{45}}\texttt{\symbol{45}}212},
  printedkey =       {BH78}
}
@book{ brow:hig:siv,
  author =           {Brown, R. and Higgins, P. J. and Sivera, R.},
  title =            {Nonabelian algrebraic topology},
  publisher =        {European Mathematical Society},
  series =           {Tracts in Mathematics},
  volume =           {15},
  year =             {2011},
  printedkey =       {BHS11}
}
@article{ brow:lod,
  author =           {Brown, R. and Loday, J.\texttt{\symbol{45}}L.},
  title =            {Van {K}ampen theorems for diagram of spaces},
  journal =          {Topology},
  volume =           {26},
  year =             {1987},
  pages =            {311\texttt{\symbol{45}}\texttt{\symbol{45}}335},
  printedkey =       {BL87}
}
@article{ BW1,
  author =           {Brown, R. and Wensley, C. D.},
  title =            {On  finite  induced  crossed modules, and the homotopy
                      $2$\texttt{\symbol{45}}type of mapping cones},
  journal =          {Theory and Applications of Categories},
  volume =           {1},
  year =             {1995},
  pages =            {54\texttt{\symbol{45}}\texttt{\symbol{45}}71},
  printedkey =       {BW95}
}
@article{ BW2,
  author =           {Brown, R. and Wensley, C. D.},
  title =            {Computing crossed modules induced by an inclusion of a
                      normal   subgroup,   with   applications  to  homotopy
                      $2$\texttt{\symbol{45}}types},
  journal =          {Theory and Applications of Categories},
  volume =           {2},
  year =             {1996},
  pages =            {3\texttt{\symbol{45}}\texttt{\symbol{45}}16},
  printedkey =       {BW96}
}
@article{ BW3,
  author =           {Brown, R. and Wensley, C. D.},
  title =            {Computation  and  homotopical  applications of induced
                      crossed modules},
  journal =          {J. Symbolic Computation},
  volume =           {35},
  year =             {2003},
  pages =            {59\texttt{\symbol{45}}\texttt{\symbol{45}}72},
  printedkey =       {BW03}
}
@phdthesis{ E1,
  author =           {Ellis, G.},
  title =            {Crossed modules and their higher dimensional analogues},
  school =           {University of Wales, Bangor},
  year =             {1984},
  printedkey =       {Ell84}
}
@article{ ell:st,
  author =           {Ellis, G. and Steiner, R.},
  title =            {Higher  dimensional  crossed  modules and the homotopy
                      groups of (n+1)\texttt{\symbol{45}}ads.},
  journal =          {J. Pure and Appl. Algebra},
  volume =           {46},
  year =             {1987},
  pages =            {117\texttt{\symbol{45}}\texttt{\symbol{45}}136},
  printedkey =       {ES87}
}
@article{ EL,
  author =           {Ellis, G. J. and Le, V. L.},
  title =            {Homotopy 2\texttt{\symbol{45}}types of low order},
  journal =          {Experimental Math.},
  volume =           {23},
  year =             {2014},
  pages =            {383\texttt{\symbol{45}}\texttt{\symbol{45}}389},
  printedkey =       {EL14}
}
@article{ G1,
  author =           {Gilbert, N. D.},
  title =            {Derivations, automorphisms and crossed modules},
  journal =          {Comm. in Algebra},
  volume =           {18},
  year =             {1990},
  pages =            {2703\texttt{\symbol{45}}\texttt{\symbol{45}}2734},
  printedkey =       {Gil90}
}
@article{ IOU1,
  author =           {Ilgaz, E. and Odabas, A. and Uslu, E. O.},
  title =            {Isoclinism of crossed modules},
  journal =          {J. Symb. Comput.},
  volume =           {},
  year =             {2016},
  pages =            {1\texttt{\symbol{45}}\texttt{\symbol{45}}17},
  note =             {https://doi.org/10.1016/j.jsc.2015.08.006},
  printedkey =       {IOU16}
}
@article{ JNO,
  author =           {James, R. and Newman, M. F. and O'Brien, E. A.},
  title =            {The groups of order 128},
  journal =          {J. Algebra},
  volume =           {129},
  year =             {1990},
  pages =            {136\texttt{\symbol{45}}\texttt{\symbol{45}}158},
  printedkey =       {JNO90}
}
@article{ L1,
  author =           {Loday, J.\texttt{\symbol{45}}L.},
  title =            {Spaces           with           finitely          many
                      non\texttt{\symbol{45}}trivial homotopy groups},
  journal =          {J. App. Algebra},
  volume =           {24},
  year =             {1982},
  pages =            {179\texttt{\symbol{45}}\texttt{\symbol{45}}202},
  printedkey =       {Lod82}
}
@article{ MW,
  author =           {Mac Lane, S. and Whitehead, J. H. C.},
  title =            {On the 3\texttt{\symbol{45}}type of a complex},
  journal =          {Proc. Nat. Acad. Sci. U.S.A.},
  volume =           {37},
  year =             {1950},
  pages =            {41\texttt{\symbol{45}}\texttt{\symbol{45}}48},
  printedkey =       {LW50}
}
@phdthesis{ M1,
  author =           {Moore, E. J.},
  title =            {Graphs  of  Groups: Word Computations and Free Crossed
                      Resolutions},
  school =           {University of Wales, Bangor},
  year =             {2001},
  printedkey =       {Moo01}
}
@phdthesis{ N2,
  author =           {Norrie, K. J.},
  title =            {Crossed modules and analogues of group theorems},
  school =           {King's College, University of London},
  year =             {1987},
  printedkey =       {Nor87}
}
@article{ N1,
  author =           {Norrie, K. J.},
  title =            {Actions and automorphisms of crossed modules},
  journal =          {Bull. Soc. Math. France},
  volume =           {118},
  year =             {1990},
  pages =            {129\texttt{\symbol{45}}\texttt{\symbol{45}}146},
  printedkey =       {Nor90}
}
@article{ W2,
  author =           {Whitehead, J. H. C.},
  title =            {On operators in relative homotopy groups},
  journal =          {Ann. of Math.},
  volume =           {49},
  year =             {1948},
  pages =            {610\texttt{\symbol{45}}\texttt{\symbol{45}}640},
  printedkey =       {Whi48}
}
@article{ W1,
  author =           {Whitehead, J. H. C.},
  title =            {Combinatorial homotopy {I}{I}},
  journal =          {Bull. Amer. Math. Soc.},
  volume =           {55},
  year =             {1949},
  pages =            {453\texttt{\symbol{45}}\texttt{\symbol{45}}496},
  printedkey =       {Whi49}
}