On the regularity and non-regularity of elliptic and parabolic systems John, O.; Stará, J. — 1990 Equadiff 7
Classical solution to a second order nonlinear elliptic system in R 3 J. Nečas; J. Stará; R. Švarc — 1978 Annali della Scuola Normale Superiore di Pisa - Classe di Scienze