1. R.P. Agarwal and D. O'Regan, A coupled system of difference equations, Appl. Math. Comp. (to appear).
2. Boundary Value Problems for Higher Order Differential Equations;Agarwal,1986
3. R.P. Agarwal, D. O'Regan and P.J.Y. Wong, Positive Solutions of Differential, Difference and Integral Equations, Kluwer, Dordrecht (to appear).
4. Existence of solutions for singular boundary value problems for higher order differential equations;Agarwal,1995
5. Advanced Topics in Difference Equations;Agarwal,1997