Demetriou IC. A theorem for piecewise convex - concave data approximation. Journal of Computational and Applied Mathematics . 2004;Vol. 164-165:245-254.

Demetriou IC. The univariate best L1 regression with one sign change in the second differences (Η μονομεταβλητή L1 άριστη παλινδρόμηση με μια αλλαγή προσήμου στις δεύτερες διαφορές). In: Proceedings of the 17th Hellenic Conference on Statistics, Lefkada, Greek Statistical Institute . ; 2004. pp. 135-142.

Demetriou IC. Least squares convex-concave data smoothing. Computational Optimization and Applications. 2004;29:197-217.

Demetriou IC. A theorem for piecewise convex–concave data approximation. Journal of Computational and Applied Mathematics. 2004;164-165:245–254.