Oscillation of second order damped elliptic differential equations

We establish some new oscillation theorems for the second order damped elliptic differential equation ∑i,j=1NDi[aij(x)Djy]+∑i=1Nbi(x)Diy+C(x,y)=0. Our results are extensions of those for second order ordinary differential equations obtained by Sun [Y.G. Sun, New Kamanev-type oscillation criteria of second order nonlinear differential euqations with damping, J. Math. Anal. Appl. 291 (2004) 341–351].