Demarks about certain first-order linear pdf in two variables

Solvability of a first order linear partial differential equation

Louis Nirenberg, François Trèves · Communications on Pure and Applied Mathematics · 1963 · 154 citations

Natural Sciences, Mathematics, Differential Equations +11

An outline of the theory of pseudoanalytic functions

Lipman Bers · Bulletin of the American Mathematical Society · 1956 · 104 citations · Full text

Natural Sciences, Mathematics, Complex Systems +6

Differential equations without solutions

Lars Hörmander · Mathematische Annalen · 1960 · 71 citations

Natural Sciences, Mathematics, Differential Equations +4