- document
- Witte, Jan H. (author) journal article 1969
- document
- Witte, Jan H. (author) journal article 1969
- document
- Witte, Jan H. (author) report 1966
- document
- Witte, Jan H. (author) journal article 1966
- document
- Witte, Jan H. (author) journal article 1966
- document
- Witte, Jan H. (author) journal article 1966