Some theorems on second order partial differential inequalities of parabolic type S. Brzychczy — 1964 Annales Polonici Mathematici
Existence of solutions for non-linear systems of differential-functional equations of parabolic type in an arbitrary domain S. Brzychczy — 1987 Annales Polonici Mathematici
On a certain property of a transformation in Hilbert space in connection with the theory of differential equations S. Brzychczy — 1967 Colloquium Mathematicae