The existence of three nontrivial solutions is established for a class of fourth-order elliptic equations. Our technical approach is based on Linking Theorem and ($\nabla$)-Theorem.
"Existence of three nontrivial solutions for a class of fourth-order elliptic equations." Topol. Methods Nonlinear Anal. 51 (2) 331 - 344, 2018. https://doi.org/10.12775/TMNA.2018.001