Multiple solutions of the periodic boundary value problem for some forced pendulum-type equations

Dual variational methods in critical point theory and applications

Antonio Ambrosetti, Paul H. Rabinowitz · Journal of Functional Analysis · 1973 · 4.4K citations

Natural Sciences, Mathematics, Physics +14

Nonconvex minimization problems

Ivar Ekeland · Bulletin of the American Mathematical Society · 1979 · 1K citations · Full text

Natural Sciences, Mathematics, Cost-minimization Analysis +16

A generalized Morse theory

Richard S. Palais, Stephen T. Smale · Bulletin of the American Mathematical Society · 1964 · 300 citations · Full text

Natural Sciences, Mathematics, Computational Geometry +12

Free vibrations for a nonlinear wave equation and a theorem of P. Rabinowitz

Haïm Brézis, Jean‐Michel Coron, Louis Nirenberg · Communications on Pure and Applied Mathematics · 1980 · 194 citations

Natural Sciences, Mathematics, Mechanical Engineering +17

A note on degree theory for gradient mappings

Herbert Amann · Proceedings of the American Mathematical Society · 1982 · 115 citations · Full text

Natural Sciences, Mathematics, Optimization +7