... when for instance, a(.) belongs to the general class of nonnegative measurable potentials d(R) of admissible potentials in R introduced in the works due to S. Cano-Casanova and J. L6pez-G6mez5, ... 2, 125-146, (1971). 2. H. Amann, Nonlinear elliptic equations with nonlinear boundary conditions, New Developments in Differential Equations, Ed. W. Eckhaus, 1976. 3. H. Amann, Israel ... L6pez-G6mez, Journal of Differential Equations 146, 336- 374, (1998). 5. S. Cano-Casanova and J. L6pez-G6mez, Journal of Differential Equations 6. S. Cano-Casanova and J. L6pez-G6mez,...