1. The brain state in a convex body neural model. Master's Thesis, San Diego State University, 1992.

2. Ein Oszillationssatz fuer Sturm-Liouvillesche Eigenwertprobleme. Master's Thesis, University Ulm, 1993.

3. Zur Positivitaet diskreter quadratischer Funktionale. PhD Thesis, University Ulm, 1995. English Edition: On Positivity of discrete quadratic functionals.

4. Controllability and disconjugacy for linear Hamiltonian difference systems. In S. Elaydi, J. Graef, G. Ladas, and A. Peterson, editors, Conference Proceedings of the First International Conference on Difference Equations, pages 65-77, San Antonio, 1994. Gordon and Breach.

5. Inhomogeneous discrete variational problems. In S. Elaydi, I. Gyoeri, and G. Ladas, editors, Conference Proceedings of the Second International Conference on Difference Equations, pages 89-97, Veszprem, 1995. Gordon and Breach.

6. Positive definiteness of discrete quadratic functionals. In C. Bandle, editor, International Series of Numerical Mathematics, volume 123, pages 55-60, Basel, 1997. Birkhaeuser. General Inequalities 7, Oberwolfach.

7. Brain state in a convex body (with S. Hui). IEEE Transactions of Neural Networks, 6(5): 1053-1060, 1995.

8. An oscillation theorem for a Sturm-Liouville eigenvalue problem. Mathematische Nachrichten, 182: 67-72, 1996.

9. Linear Hamiltonian difference systems: disconjugacy and Jacobi-type conditions. Journal of Mathematical Analysis and Applications, 199(3): 804-826, 1996.

10. On disconjugacy for Sturm-Liouville difference equations. Journal of Difference Equations and Applications, 2(2): 227-237, 1996.

11. Riccati matrix difference equations and linear Hamiltonian difference systems. Dynamics of Continuos, Discrete and Impulsive Systems, 2(2): 147-159, 1996.

12. Disconjugacy and transformations for symplectic systems (with O. Dosly). The Rocky Mountain Journal of Mathematics. To appear.

13. Discrete linear Hamiltonian eigenvalue problems. Computers and Mathematics with Applications. To appear.

14. Symplectic systems and related discrete quadratic functionals. Facta Universitatis (Ser. Math. Inform.). To appear.

15. Asymptotic behavior of discretized Sturm-Liouville eigenvalue problems. Journal of Differrence Equations and Applications. To appear.

16. Inequalities and asymptotics for Riccati matrix difference operators (with O. Dosly and W. Kratz). Submitted.

17. Discrete Sturmian Theory. Mathematical Inequalitites and Applications. To appear. Preprint in Ulmer Seminare 1.

18. Positivity of block tridiagonal matrices (with O. Dosly). Submitted.

19. Quadratic functionals for second order matrix equations on time scales (with R. P. Agarwal). Nonlinear Analysis. To appear. Preprint in Research Report No. 701, Department of Mathematics, National University of Singapore.

20. Positive solutions and eigenvalues of conjugate boundary value problems (with R. P. Agarwal and P. J. Y. Wong). Submitted. Preprint in Research Report No. 702, Department of Mathematics, National University of Singapore.

21. Basic calculus on time scales and some of its applications (with R. P. Agarwal). Submitted. Preprint in Research Report No. 704, Department of Mathematics, National University of Singapore.

22. A Sturmian theorem for recessive solutions of linear Hamiltonian difference systems (with O. Dosly and W. Kratz). Applied Mathematics Letters. To appear.

23. Sturm-Liouville eigenvalue problems on time scales (with R. P. Agarwal and P. J. Y. Wong). Applied Mathematics and Computations. To appear. Preprint in Research Report No. 714, Department of Mathematics, National University of Singapore.

24. Discrete Reid roundabout theorems (with O. Dosly and W. Kratz). Dynamic Systems and Applications. To appear.

25. On eigenvalues and eigenfunctions of discrete conjugate boundary value problems (with R. P. Agarwal and P. J. Y. Wong). Submitted.