A Second Order Differential Equation with Singular Solutions

Recurrent geodesics on a surface of negative curvature

Harold Marston Morse · Transactions of the American Mathematical Society · 1921 · 399 citations · Full text

Natural Sciences, Physics, Geometry +11

Surface transformations and their dynamical applications

George D. Birkhoff · Acta Mathematica · 1922 · 342 citations · Full text

Natural Sciences, Mathematics, Physics +13

Transformation Theory of Non-Linear Differential Equations of the Second Order

Norman Levinson · Annals of Mathematics · 1944 · 164 citations

Natural Sciences, Mathematics, Physics +9

A Simple Second Order Differential Equation with Singular Motions

Norman Levinson · Proceedings of the National Academy of Sciences · 1948 · 16 citations · Full text

Natural Resources, Water Resources Management, Environmental Economics +14