Solvability and hypoellipticity of first order partial differential operators and ...
Solvability and hypoellipticity of first order partial differential operators and...
Solvability for a class of first-order partial differential operators
Semiglobal solvability for classes of non singular vector fields
Vector fields, sums of squares and Bers-Vekua equations: existence and regularity ...
Existence of periodic solutions for first-order partial differential equations