“…In what concerns the eigenvalue problems involving quasilinear operators we remember, in the case of homogeneous elliptic operators, the contributions of Anane [1], de Thélin [14], Lindqvist [7] and Filippucci-Pucci-Rȃdulescu [5], while in the case of nonhomogeneous elliptic operators we point out the recent advances of Fan-Zhang-Zhao [4], Mihȃilescu-Rȃdulescu [10,11,12], Mihȃilescu-Pucci-Rȃdulescu [8,9] and Fan [3].…”