An O(n) Algorithm for Least Squares Quasi-convex Approximation, Computers and Mathematics with Applications, An International Journal, Vol. 14, No. 8, 1987, pp. 583-590.

An Asymptotic Result for the Degree of Approximation by Monotone Polynomials, Journal of Approximation Theory, Vol. 53, No. 1, April 1988, pp. 78-85.

Uniform Approximation by Quasi-convex and Convex Functions (an abstract of this paper appears in Abstracts of the American Mathematical Society, Vol. 7, No. 4, August 1986, p.ÿ283), Journal of Approximation Theory, Vol. 55, No. 3, December 1988, pp. 326-336.

Lipschitzian Selections in Approximation from Nonconvex sets of Bounded Functions, Journal of Approximation Theory, Vol. 56, No. 2, February 1989, 217-224.

Lp - Approximation by Quasi-convex and Convex Functions, Journal of Mathematical Analysis and Applications, Vol. 139, No. 2, May 1989, pp. 574-585.

Lp - Approximation from Nonconvex Subsets of Special Classes of Functions, Journal of Approximation Theory, Vol. 57, No. 2, May 1989, pp. 223-238.

Lipschitzian Selections in Best Approximation by Continuous Functions, Journal of Approximation Theory, Vol. 61, No. 1, April 1990, pp. 40-52.

Lp - Approximation by Subsets of Convex Functions of Several Variables, Journal of Approximation Theory, Vol. 63, No. 2, November 1990, pp. 144-155.

Best Piecewise Monotone Uniform Approximation (with S.E. Weinstein and Y. Xu), Journal of Approximation Theory, Vol. 63, No. 3, December 1990, pp. 375-383.

Duality and Lipschitzian Selections in Best Approximation from Nonconvex Cones, Journal of Approximation Theory, Vol. 64, No. 3, March 1991, pp. 315-342.

Uniform Approximation by a Nonconvex Cone of Continuous Functions, Journal of Approximation Theory, Vol. 68, No. 1, January 1992, pp. 83-112.

Generalized Convex Functions and Best Lp - Approximation (with R. M. Mathsen), Proceedings of the American Mathematical Society, Vol. 114, No. 3, March 1992, pp. 733-740.

Dual Cones, Constrained n-Convex Lp - Approximation and Perfect Splines (with F. Deutsch and Y. Xu), Journal of Approximation Theory, Vol. 80, No. 2, February 1995, pp. 180-203.

Constrained Lp -Approximation by Generalized Convex Functions Induced by ECT-Systems, Journal of Approximation Theory, Vol. 80, No. 3, March 1995, pp. 423-449.

Constrained Best Approximation in Hilbert Space III, Applications to N-Convex Functions (with F. Deutsch, J.D. Ward and Y. Xu),  Constructive Approximation (Journal), Vol. 12, 1996, pp. 361-384.

Integer Isotone Optimization (with M.-H. Liu), SIAM Journal on Optimization, Vol. 7, No. 4, November 1997, pp. 1152-1159.

Minimizing Separable Convex Functions Subject to Simple Chain Constraints (with M. J. Best and N. Chakravarti), SIAM Journal on Optimization, Vol. 10, No. 3, pp.658-672, 2000.

Best Approximation by Bounded or Continuous Functions, Encyclopedia of Optimization, Kluwer Academic Publishers, Vol. I, pp. 127-131, 2001 (invited article).

Regression by Special Functions, Encyclopedia of Optimization, Kluwer Academic Publishers, Vol. 5, pp. 12-16, 2001 (invited article).

Fitting a Least Squares Piecewise Linear Continuous Curve in Two Dimensions (with S. Kundu), Computers and Mathematics with Applications, an International Journal, Vol. 41, pp. 1033-1041, 2001.

Isotone  Functions, Dual Cones and Networks, Applied Mathematics Letters, Vol. 14, pp.463-467, 2001.

An Algorithm for Approximation by Quasi-convex Functions on R^m , Computers and Mathematics with Applications, an International Journal, accepted for publication, 2002.