1. On the range of the sum of nonlinear operators. In: New Developments in Differential Equations (ed. ), pp. 65–71. North-Holland Publ. Comp. 1976
2. Image d’une somme d’operateurs monotones et applications
3. Landesman-Lazer'S Type Problems for Nonlinear Equations. Conf. Sem. Matem. Univ. Bari 1977, 1–22