Garding's inequality for elliptic differential operator with infinite number of variables.
Ger-type and Hyers--Ulam stabilities for the first-order linear differential operators of entire functions.
Global solutions of semilinear heat equations in Hilbert spaces.
Green's function and convergence of Fourier series for elliptic differential operators with potential from Kato space.
Group Actions on the Solutions of Linear Partial Differential Equations.