Acta Mathematica · 1976 · 1.1K citations · 7 references
Natural SciencesMathematicsDifferential EquationsCohomology TheoryDifferential GeometryDifferential TopologyGroup TheoryOperator TheorySpectral TheoryNilpotent Groups
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Hypoelliptic second order differential equations
Lars Hörmander · Acta Mathematica · 1967 · 2.4K citations · Full text
Intermediate spaces and interpolation, the complex method
A. Calderón · Studia Mathematica · 1964 · 1K citations · Full text
Gerald B. Folland, E. M. Stein · Communications on Pure and Applied Mathematics · 1974 · 972 citations