Two kinds of normality in vector optimization. - Jonathan M. Borwein; J. W. Nieuwenhuis (Math. Program., 1984)

Continuity of dynamical systems: A system theoretic approach. - J. W. Nieuwenhuis; Jan C. Willems (Math. Control. Signals Syst., 1988)

On the nature of descriptor systems. - J. W. Nieuwenhuis; Jan C. Willems (Kybernetika, 1991)

Continuity of dynamical systems: The continuous-time case. - J. W. Nieuwenhuis; Jan C. Willems (Math. Control. Signals Syst., 1992)