31-XX	Potential theory {For probabilistic potential theory, see 60J45}
31-00	General reference works (handbooks, dictionaries, bibliographies, etc.)
31-01	Instructional exposition (textbooks, tutorial papers, etc.)
31-02	Research exposition (monographs, survey articles)
31-03	Historical {!must also be assigned at least one classification number from section 01}
31-04	Explicit machine computation and programs (not the theory of computation or programming)
31-06	Proceedings, conferences, collections, etc.
31Axx	Two-dimensional theory
31A05	Harmonic, subharmonic, superharmonic functions
31A10	Integral representations, integral operators, integral equations methods
31A15	Potentials and capacity, harmonic measure, extremal length [See also 30C85]
31A20	Boundary behavior (theorems of Fatou type, etc.)
31A25	Boundary value and inverse problems
31A30	Biharmonic, polyharmonic functions and equations, Poisson's equation
31A35	Connections with differential equations
31A99	None of the above, but in this section
31Bxx	Higher-dimensional theory
31B05	Harmonic, subharmonic, superharmonic functions
31B10	Integral representations, integral operators, integral equations methods
31B15	Potentials and capacities, extremal length
31B20	Boundary value and inverse problems
31B25	Boundary behavior
31B30	Biharmonic and polyharmonic equations and functions
31B35	Connections with differential equations
31B99	None of the above, but in this section
31Cxx	Other generalizations
31C05	Harmonic, subharmonic, superharmonic functions
31C10	Pluriharmonic and plurisubharmonic functions [See also 32U05]
31C12	Potential theory on Riemannian manifolds [See also 53C20] {For Hodge theory, see 58A14}
31C15	Potentials and capacities
31C20	Discrete potential theory and numerical methods
31C25	Dirichlet spaces
31C35	Martin boundary theory [See also 60J50]
31C40	Fine potential theory
31C45	Other generalizations (nonlinear potential theory, etc.)
31C99	None of the above, but in this section
31D05	Axiomatic potential theory