Multiplicity results of positive solutions for fourth-order nonlinear differential equation with singularity.

By application of Green's function and some fixed-point theorems, that is, Leray-Schauder alternative principle and Schauder's fixed-point theorem, we establish two newexistence results of positive periodic solutions for nonlinear fourthorder singular differential equation, which extend and improve significantly existing results in the literature. [ABSTRACT FROM AUTHOR]