Vandyck, M. A. (1987) On the Problem of Space-time Symmetries in the Theory of Supergravity (Part II). (Preprint)
Vandyck, M. A. (1987) On the Time Evolution of some Robinson-Trautman Line Elements. (Preprint)
Vandyck, M. A. (1991) A Remark on the Twin “Paradox”. (Preprint)