TY - JOUR AU - A. V. Bitsadze TI - On the theory of systems of partial differential equations JO - Trudy Matematicheskogo Instituta imeni V.A. Steklova PY - 1976 SP - 67 EP - 77 VL - 142 PB - mathdoc UR - http://geodesic.mathdoc.fr/item/TM_1976_142_a3/ LA - ru ID - TM_1976_142_a3 ER -