47XX OPERATOR THEORY
 4700 General reference works (handbooks, dictionaries, bibliographies, etc.)
 4701 Instructional exposition (textbooks, tutorial papers, etc.)
 4702 Research exposition (monographs, survey articles)
 4703 Historical (must also be assigned at least one classification number from Section 01)
 4704 Explicit machine computation and programs (not the theory of computation or programming)
 4706 Proceedings, conferences, collections, etc.

47Axx General theory of linear operators
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47Bxx Special classes of linear operators
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 47Cxx Individual linear operators as elements of algebraic systems
 47Dxx Groups and semigroups of linear operators, their generalizations and applications
 47Exx Ordinary differential operators [See also 34Bxx, 34Lxx]
 47Fxx Partial differential operators [See also 35Pxx, 58Jxx]
 47Gxx Integral, integrodifferential, and pseudodifferential operators [See also 58Jxx]
 47Hxx Nonlinear operators and their properties (For global and geometric aspects, see 58XX, especially 58Cxx)
 47Jxx Equations and inequalities involving nonlinear operators [See also 46Txx] (For global and geometric aspects, see 58XX)
 47Lxx Linear spaces and algebras of operators [See also 46Lxx]

47Nxx Miscellaneous applications of operator theory [See also 46Nxx]
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 47Sxx Other (nonclassical) types of operator theory [See also 46Sxx]