TY - JOUR AU - E. C. Zachmanoglou TI - Solutions which are flat or Singular on Totally Characteristic Manifolds of first order Partial Differential Equations JO - Ευκλείδης Γ PY - 1988 SP - 149 EP - 158 VL - 20 PB - mathdoc UR - http://geodesic.mathdoc.fr/item/EUG_1988__20_a13/ LA - gr ID - EUG_1988__20_a13 ER -