1. On elliptic equations with piecewise constant coefficients I, Applicable Analysis 2 (1972), 79-96;

2. On elliptic equations with piecewise constant coefficients II,  Ann. Scuola Norm. Sup. 26 (1972), 830-870;

3. A mixed problem for the Laplace equation in a right angle with an oblique derivative given on a side of the angle, Ann. Mat. Pura Appl. 100 (1974), 259-306;

4. A mixed boundary value problem for the Laplace equation in an angle (1-st part), Rend. Sem. Mat. Univ. Padova 54 (1975), 147-183;

5. A mixed boundary value problem for the Laplace equation in an angle (2-nd part), Rend. Sem. Mat. Univ. Padova 55 (1976), 7-43;

6. On elliptic equations with piecewise constant coefficients III (part I), Le Matematiche 30 (1975), 241-277;  

7. On elliptic equations with piecewise constant coefficients III (part II), Le Matematiche 31 (1976), 1-39;

8. The Dirichlet problem for an elliptic equation in an angle with leading homogeneous measurable coefficients, Ann. Mat. Pura Appl. 115 (1977),  41-97; 

9. Mixed boundary value problems for non--variational elliptic equations on a polygon, Boll. Un. Mat. Ital. 15B (1978), 401-435;

10.  Boundary value problems for first--order elliptic systems on domains with polygonal boundaries I, Boll. Un. Mat. Ital. 17B (1980), 125-185; 

11. Boundary value problems for first--order elliptic systems on domains  with polygonal boundaries II, Analisi Funzionale ed Appl. Suppl.Boll. Un. Mat. Ital. 1 (1980), 93-128.