1. Oscillation Theory for Difference and Functional Differential Equations;Agarwal,2002
2. Oscillation Theory for Second Order Linear, Half-linear, Superlinear and Sublinear Dynamic Equations;Agarwal,2002
3. Inequalities;Beckenbach,1961
4. Oscillation theorems for a nonlinear analogue for Hill’s equation;Butler;Quart. J. Math. (Oxford),1976
5. Intergral averages and oscillation of second order nonlinear differential equations;Butler;SIAM J. Math. Anal.,1980