1. Baculíková, B, Džurina, J: Oscillation theorems for second-order nonlinear neutral differential equations. Comput. Math. Appl. 62, 4472-4478 (2011)
2. Baculíková, B, Džurina, J: Oscillation theorems for higher order neutral differential equations. Appl. Math. Comput. 219, 3769-3778 (2012)
3. Baculíková, B, Džurina, J, Li, T: Oscillation results for even-order quasilinear neutral functional differential equations. Electron. J. Differ. Equ. 2011, 143 (2011)
4. El-Sayed, MA: An oscillation criterion for a forced second order linear differential equation. Proc. Am. Math. Soc. 118, 813-817 (1993)
5. Erbe, L, Kong, Q, Zhang, BG: Oscillation Theory for Functional Differential Equations. Dekker, New York (1995)