Applicability of nonlinear optimization in decision support systems : the development of a flexible optimizer / door Wilhelmina Janna KribbeApplicability of nonlinear programming in decision support systems : realization of user-friendly software / Willeke Kribbe & Gerard van der HoekApplicability of nonlinear programming in decision support systems : realization of user-friendly software / Willeke Kribbe and Gerard van der HoekManagement van informatiesysteembeheer / W.J. Kribbe, J. Sietsma