1Agarwal R P. Difference Equations and Inequalities. Theory, Methods and Applications [M]. second ed. New York.. Marcel Dekker, 2000,228.
2Agarwal R P,Perera K, D O' Regan. Multiple positive solutions of singular discrete p-Laplacian problems via variational methods[J]. Adv Difference Equ, 2005,2: 93-99.
3Atici F M,Cabada A. Existence and uniqueness results for discrete second-order periodic boundary value prob- lems[J]. Corn Math Appl, 2003,45 : 1417-1427.
4Ma R,Lu Y. Existence of one-signed solutions of discrete second-order periodic boundary value problems[J]. Abst Appl Anal Volume, 2012(2012), Article ID 437912,13 Pages. doi: 10 1155/2012/437912.
5Cabada A,Cid J A. Existence and multiplicity of solutions for a periodic Hill's equation with parametric depend- ence and singularities[J]. Abst Appl Anal Volum, 2011 (2011), Article ID 545264,19 Pages. doi: 10 1155/2011/ 545264.
6Bereanu C, Mawhin J. Existence and multiplicity results for periodic solutions of nonlinear difference equations [J]. J Difference Equ App1,2006,12 : 677-695.
7Bereanu C, Mawhin J. Existence and multiplicity results for nonlinear second order difference equations with Dirichlet boundary conditions[J]. Math Bohem, 2006,131 : 145-160.
8Cabada A,Iannizzotto A, Tersian S. Multiple solutions for discrete boundary value problems[J]. J Math Anal Appl, 2009,356 : 418-428.
9Cabada A, Otero-Espinar V. Optimal existence results for nth order periodic boundary value difference equations [J]. J Math Anal Appl, 2000,247 : 67-86.