45XX INTEGRAL EQUATIONS
 4500 General reference works (handbooks, dictionaries, bibliographies, etc.)
 4501 Instructional exposition (textbooks, tutorial papers, etc.)
 4502 Research exposition (monographs, survey articles)
 4503 Historical (must also be assigned at least one classification number from Section 01)
 4504 Explicit machine computation and programs (not the theory of computation or programming)
 4506 Proceedings, conferences, collections, etc.
 45Axx Linear integral equations
 45Bxx Fredholm integral equations
 45Cxx Eigenvalue problems [See also 34Lxx, 35Pxx, 45P05, 47A75]
 45Dxx Volterra integral equations [See also 34A12]
 45Exx Singular integral equations [See also 30E20, 30E25, 44A15, 44A35]
 45Fxx Systems of linear integral equations
 45Gxx Nonlinear integral equations [See also 47H30, 47Jxx]
 45Hxx Miscellaneous special kernels [See also 44A15]
 45Jxx Integroordinary differential equations [See also 34K05, 34K30, 47G20]

45Kxx Integropartial differential equations [See also 34K30, 35R09, 35R10, 47G20]
(1)
 45Lxx Theoretical approximation of solutions (For numerical analysis, see 65Rxx)
 45Mxx Qualitative behavior
 45Nxx Abstract integral equations, integral equations in abstract spaces
 45Pxx Integral operators [See also 47B38, 47G10]
 45Qxx Inverse problems
 45Rxx Random integral equations [See also 60H20]