Weak singularities may help periodic solutions to exist

Existence of one-signed periodic solutions of some second-order differential equations via a Krasnoselskii fixed point theorem

Pedro J. Torres · Journal of Differential Equations · 2003 · 287 citations

Natural Sciences, Mathematics, Differential Equations +10

Conservative dynamical systems involving strong forces

William B. Gordon · Transactions of the American Mathematical Society · 1975 · 221 citations

Natural Sciences, Mathematics, Physics +10

A Minimizing Property of Keplerian Orbits

William B. Gordon · American Journal of Mathematics · 1977 · 193 citations

Engineering, Aerospace Engineering, Mathematics +14

Multiplicity of positive periodic solutions to superlinear repulsive singular equations

Daqing Jiang, Jifeng Chu, Meirong Zhang · Journal of Differential Equations · 2005 · 140 citations

Natural Sciences, Mathematics, Differential Equations +8

Existence of Nonnegative and Nonpositive Solutions for Second Order Periodic Boundary Value Problems

Irena Rachůnková, Milan Tvrdý, Ivo Vrkoč · Journal of Differential Equations · 2001 · 132 citations

Natural Sciences, Mathematics, Differential Equations +10