Existence, comparison, and compactness results for quasilinear variational-hemivariational inequalities. - Siegfried Carl; Vy Khoi Le; Dumitru Motreanu (Int. J. Math. Math. Sci., 2005)

Vector Quasi-Hemivariational Inequalities and Discontinuous Elliptic Systems. - Siegfried Carl; Zdzislaw Naniewicz (J. Glob. Optim., 2006)