“…In recent years, more and more attention have been paid to the existence and multiplicity of nonnegative or positive solutions for the elliptic problems involving concave terms and critical Sobolev exponent. Results relating to these problems can be found in [1], [2], [4,5,12,13], [7,8,9], [11,14,15,16,17,18,19,20,21], and the references therein. By the results of the above papers we know that the number of nontrivial solutions for problem (1) is affected by the concave-convex nonlinearities.…”