49-00 General reference works (handbooks, dictionaries, bibliographies, etc.)
49-01 Instructional exposition (textbooks, tutorial papers, etc.)
49-02 Research exposition (monographs, survey articles)
49-03 Historical (must also be assigned at least one classification number from Section 01)
49-04 Explicit machine computation and programs (not the theory of computation or programming)
49-06 Proceedings, conferences, collections, etc.
49Jxx Existence theories
49Kxx Necessary conditions and sufficient conditions for optimality
49Lxx Hamilton-Jacobi theories, including dynamic programming
49Mxx Methods of successive approximations [See also 90Cxx, 65Kxx]
49Nxx Miscellaneous topics
49Qxx Manifolds [See also 58Exx]
49R50 Variational methods for eigenvalues of operators [See also 47A75]
49S05 Variational principles of physics