en Connolly, Francis; Davis, James (august 2004). „The surgery obstruction groups of the infinite dihedral group”. Geometry & Topology. 8 (3): 1043–1078. arXiv:math/0306054. doi:10.2140/gt.2004.8.1043.
books.google.com
en Meenaxi Bhattacharjee, Dugald Macpherson, Rögnvaldur G. Möller, Peter M. Neumann. Notes on Infinite Permutation Groups, Issue 1689. Springer, 1998. p. 38. ISBN: 978-3-540-64965-6
doi.org
en Connolly, Francis; Davis, James (august 2004). „The surgery obstruction groups of the infinite dihedral group”. Geometry & Topology. 8 (3): 1043–1078. arXiv:math/0306054. doi:10.2140/gt.2004.8.1043.