1. Agarwal, R.P.: Difference equations and inequalities. In: Theory, Methods and Applications, 2nd edn. Dekker, New York (2000)
2. Agarwal, R.P., Grace, S.R., O’Regan, D.: Oscillation criteria for certain nth order differential equations with deviating arguments. J. Math. Anal. Appl. 262, 601–622 (2001)
3. Cheng, W.Z., She, Y.J.: Oscillation criteria for second order nonlinear difference equations. Funkc. Ekvacioj 34, 313–319 (1991)
4. Lalli, B.S., Grace, S.R.: Oscillation theorems for second order neutral difference equations. Appl. Math. Comput. 62, 47–60 (1994)
5. Saker, S.H.: Oscillation of second-order perturbed nonlinear difference equations. Appl. Math. Comput. 144, 305–324 (2003)