Da-Xue Chen and  Guang-Hui Liu,  Oscillation Theorems for Second-order Nonlinear Neutral Dynamic Equations with Variable Delays and Damping.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    February 2011, vol. 50(2). 192 - 200
    [viewed 24 April 2024]. Available from: https://publications.waset.org/pdf/2411.