- document
- Brummelhuis, P.G.J. ten (author), Ouboter, M.R.L. (author) report 1994
- document
- Ouboter, M.R.L. (author), Eck, G.T.M. van (author) report 1994
- document
- Ouboter, M.R.L. (author), Gils, J.A.G. van (author) report 1988
- document
- Flokstra, C. (author) report 1986