The early proofs of the theorem of Campbell, Baker, Hausdorff, and Dynkin

Ordinary Differential Equations

A. T. Lonseth, E. L. Ince · National Mathematics Magazine · 1945 · 3.1K citations

Oscillation Theory, Nonlinear Equation, Financial Differential Equations +2

Hypoelliptic second order differential equations

Lars Hörmander · Acta Mathematica · 1967 · 2.4K citations · Full text

Oscillation Theory, Nonlinear Hyperbolic Problem, Nonlinear Equation

Combinatorial Group Theory.

P. M. Cohn, Wilhelm Magnus, A. Karrass et al. · American Mathematical Monthly · 1967 · 1.3K citations

Geometric Group Theory, Linear Groups, Group Theory (Abstract Algebra) +6

Exponential Operators and Parameter Differentiation in Quantum Physics

R. M. Wilcox · Journal of Mathematical Physics · 1967 · 1.2K citations

Spectral Theory, Quantum Science, Weyl Prescription +13

Hypoelliptic differential operators and nilpotent groups

Linda Preiss Rothschild, E. M. Stein · Acta Mathematica · 1976 · 1.1K citations · Full text

Lie Group, Nilpotent Group, Hypoelliptic Differential Operators +1