Flat solutions and singular solutions of linear partial differential equations with analytic coefficients E. C. Zachmanoglou Séminaire Équations aux dérivées partielles (Polytechnique)
Solutions which are flat or Singular on Totally Characteristic Manifolds of first order Partial Differential Equations E. C. Zachmanoglou — 1979 Δελτίο της Ελληνικής Μαθηματικής Εταιρίας
Unique continuation theorems for solutions of partial differential equations and inequalities Mohamed S. Baouendi; E. C. Zachmanoglou — 1977 Journées équations aux dérivées partielles