1. Karakoc F., Bereketoglu H., Seyhan G. Oscillatory and periodic solutions of impulsive differential equations with piecewise constant argument, Acta Appl. Math., 110 No. 1 (2009) 499--510.
2. Karakoc F., Ogun Unal A., Bereketoglu H. Oscillation of nonlinear differential equations with piecewise constant arguments. E. J. Qualitative Theory of Diff. Equ., 49 (2013) 1--12.