Yz. Zhang et al., OSCILLATION CRITERIA FOR IMPULSIVE DELAY-DIFFERENTIAL EQUATIONS, Journal of mathematical analysis and applications, 205(2), 1997, pp. 461-470
Some new results on oscillation and nonoscillation for delay different
ial equations with impulses are established. A counterexample is given
which shows that a known oscillation criterion is incorrect. (C) 1997
Academic Press.