**REFERENCES**

[1] R. P. Agarwal, M. Bohner, P. J. Y. Wong, Positive solutions and eigenvalues of conjugate

boundary-value problems, Proc. Edinburgh Math. Soc. 42 (1999), 349–374.

[2] R. P. Agarwal, H. L¨u, D. O’Regan, Eigenvalues and the One-Dimensional p-Laplacian, J.

Math. Anal. Appl. 266 (2002), 383–400.

[3] J. Chu, D. Jiang, Eigenvalues and discrete boundary value problems for the one-dimensional

p-Laplacian, J. Math. Anal. Appl. 305 (2005), 452- 465.

[4] P. W. Eloe, Y. N. Raffoul, D. Reid, K. Yin, Positive solutions of nonlinear functional difference

equations, Comput. Math. Appl. 42 (2001), 639–646.

[5] L. H. Erbe, H. Wang, On the existence of positive solutions of ordinary differential equations,

Proc. Amer. Math. Soc. 120 (1994), 743–748.

[6] D. Jiang, J. Wei, B. Zhang, Positive periodic solutions of functional differential equations and

population models, Electron. J. Differential Equations, 71 (2002), 1–13.

[7] D. Jiang, J. Chu, M. Zhang, Multiplicity of positive periodic solutions to superlinear repulsive

singular equations, J. Differential Equations, 211 (2005), 282–302.

[8] M. A. Krasnosel’skii, Positive Solutions of Operator Equations, Noordhoff, Groningen, 1964.

[9] K. Q. Lan, J. R. L. Webb, Positive solutions of semilinear differential equations with singularities,

J. Differential Equations, 148 (1998), 407–421.

[10] K. Q. Lan, Mulpiple positive solutions of semilinear differential equations with singularities,

J. London Math. Soc. 63 (2001), 690–704.

[11] Y. Li, Y. Kuang, Periodic solutions in periodic state-dependent delay equations and population

models, Proc. Amer. Math. Soc. 130 (2001), 1345–1353.

[12] Y. N. Raffoul, Positive periodic solutions of nonlinear functional difference equations, Electron.

J. Differential Equations, 55 (2002), 1–8.

[13] Y. N. Raffoul, Positive periodic solutions of systems of functional differential equations, J.

Korean Math. Soc. 42 (2005), 749–759.

[14] Y. N. Raffoul, C. C. Tisdell, Positive periodic solutions of functional discrete systems and

population models, Adv. Difference Equations, 3 (2005), 369–380.

[15] H. Wang, Positive periodic solutions of functional differential equations, J. Differential Equations,

202 (2004), 354–366.