Non‐coercive boundary value problems

Estimates near the boundary for solutions of elliptic partial differential equations satisfying general boundary conditions. I

Shmuel Agmon, Avron Douglis, Louis Nirenberg · Communications on Pure and Applied Mathematics · 1959 · 3.7K citations

Monge-ampere Equation, Elliptic Equation, Geometric Partial Differential Equation +4

Estimates near the boundary for solutions of elliptic partial differential equations satisfying general boundary conditions II

Shmuel Agmon, Avron Douglis, Louis Nirenberg · Communications on Pure and Applied Mathematics · 1964 · 1.3K citations

Monge-ampere Equation, Elliptic Equation, Geometric Partial Differential Equation +4

Symmetric hyperbolic linear differential equations

Kurt Friedrichs · Communications on Pure and Applied Mathematics · 1954 · 664 citations

Differential Equations, Nonlinear Hyperbolic Problem, Hyperbolic Equation +1

An algebra of pseudo‐differential operators

J. J. Kohn, Louis Nirenberg · Communications on Pure and Applied Mathematics · 1965 · 650 citations

Algebraic Analysis, Pseudo‐differential Operators, Linear Operator +1

Symmetric positive linear differential equations

Kurt Friedrichs · Communications on Pure and Applied Mathematics · 1958 · 601 citations

Lie Point Symmetry, Oscillation Theory, Nonlinear Functional Analysis