Annals of Mathematics · 1958 · 282 citations · 0 references
Natural SciencesMathematicsDifferential EquationsDynamical SystemsFunctional AnalysisInitial Value ProblemsLinear AlgebraOperator TheoryPartial Differential EquationsSystems Of Differential EquationsFunctional Analysis Of FunctionsFunctional EquationsLinear FunctionalsLinear Initial Value ProblemsLinear Partial Differential Equations