- document
- de Back, J. (author), Vaessen, G.H.G. (author) report 1981
- document
- de Back, J. (author), Vaessen, G. (author) report 1979
- document
- de Back, J. (author), Vaessen, G. (author) report 1979
- document
- de Back, J. (author), Vaessen, G. (author) report 1979
- document
- de Back, J. (author), Vaessen, G. (author) report 1978
- document
- de Back, J. (author), Vaessen, G. (author) report 1978