  We apply a recently obtained three critical points theorem of B. Ricceri to
prove the existence of at least three solutions of certain two-parameters
Dirichlet problems defined on the Sierpinski gasket. We also show the existence
of at least three nonzero solutions of certain perturbed two-parameters
Dirichlet problems on the Sierpinski gasket, using both the mountain pass
theorem of Ambrosetti-Rabinowitz and that of Pucci-Serrin.
