57-00 General reference works (handbooks, dictionaries, bibliographies, etc.)
57-01 Instructional exposition (textbooks, tutorial papers, etc.)
57-02 Research exposition (monographs, survey articles)
57-03 Historical (must also be assigned at least one classification number from Section 01)
57-04 Explicit machine computation and programs (not the theory of computation or programming)
57-06 Proceedings, conferences, collections, etc.
57Mxx Low-dimensional topology
57Nxx Topological manifolds
57Pxx Generalized manifolds [See also 18F15]
57Qxx PL-topology
57Rxx Differential topology {For foundational questions of differentiable manifolds, see 58Axx; for infinite-dimensional manifolds, see 58Bxx}
57Sxx Topological transformation groups [See also 20F34, 22-XX, 37-XX, 54H15, 58D05]
57Txx Homology and homotopy of topological groups and related structures