Ekeland's variational principle and the mountain pass lemma

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

On the variational principle

Ivar Ekeland · Journal of Mathematical Analysis and Applications · 1974 · 2.3K citations · Full text

Natural Sciences, Mathematics, Physics +10

Nonconvex minimization problems

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

Natural Sciences, Mathematics, Cost-minimization Analysis +16

Variational methods for non-differentiable functionals and their applications to partial differential equations

Kung-Ching Chang · Journal of Mathematical Analysis and Applications · 1981 · 874 citations

Natural Sciences, Mathematics, Differential Equations +13

Periodic solutions of hamiltonian systems

Paul H. Rabinowitz · Communications on Pure and Applied Mathematics · 1978 · 735 citations

Natural Sciences, Mathematics, Physics +13