35Jxx Partial differential equations of elliptic type

35J05  Laplace equation, reduced wave equation (Helmholtz),
               Poisson equation, See also {31Axx, 31Bxx}
35J10  Schrodinger operator, See also {35Pxx}
35J15  General theory of second-order, elliptic equations
35J20  Variational methods for second-order, elliptic equations
35J25  Boundary value problems for second-order, elliptic
               equations
35J30  General theory of higher-order, elliptic equations , See
               also {31A30, 31B30}
35J35  Variational methods for higher-order, elliptic equations
35J40  Boundary value problems for higher-order, elliptic
               equations
35J45  General theory of elliptic systems of PDE
35J50  Variational methods for elliptic systems
35J55  Boundary value problems for elliptic systems
35J60  Nonlinear PDE of elliptic type
35J65  Nonlinear boundary value problems for linear elliptic PDE;
               boundary value problems for nonlinear elliptic PDE
35J67  Boundary values of solutions to elliptic PDE
35J70  Elliptic partial differential equations of degenerate type
35J85  Unilateral problems and variational inequalities for
               elliptic PDE, See also {35R35, 49J40}
35J99  None of the above but in this section