On the oscillation of forced second order mixed-nonlinear elliptic equations

Oscillation theorems are established for forced second order mixed-nonlinear elliptic differential equations {div(A(x) parallel to del y parallel to(p-1) del y) + < b(x), parallel to del y parallel to(p-1)del y > + C(x,y) = e(x), C(x,y) = c(x)vertical bar y vertical bar(p-1) y + Sigma(m)(i=1) c(i)(x)vertical bar y vertical bar(pi-1)y under quite general conditions. These results are extensions of the recent results of Sun and Wong, [J. Math. Anal. Appl. 334 (2007)] and Zheng, Wang and Han [Appl. Math. Lett. 22 (2009)] for forced second order ordinary differential equations with mixed nonlinearities, and include some known oscillation results in the literature.