1. Difference Equations and Inequalities, Theory, Methods, and Applications;Agarwal,2000
2. Oscillation Theory for Difference and Functional Differential Equations;Agarwal,2000
3. Oscillation Theory of Delay Differential Equations, With Applications;Győri,1991
4. Oscillation and comparison theorems of difference equations with positive and negative coefficients;Chen;Bull. Inst. Math. Acad. Sin.,1994
5. Comparison criteria of positive solutions for a neutral difference equation with positive and negative coefficients;Guan;Acta Math. Appl. Sin. (English Ser.),1999