Perhaps you should try some spelling variations:
"methode van bavel / gtt" » "methode vi bavel / gtt", "methode v bavel / gtt", "methode vom bavel / gtt"
"methode vii bavel / gtt" » "methoden vii bavel / gtt", "methods vii bavel / gtt", "method vii bavel / gtt", "methode vii bases / gtt"
"methode von bavel / gtt" » "methode von babel / gtt", "methode von gavel / gtt", "methode von havel / gtt"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (((("methode van bavel / gtt") OR ("methode vii bavel / gtt"))) OR ("methode von bavel / gtt"))*.
• Removing quotes may allow a broader search: (((( methode van bavel / gtt ) or ( methode vii bavel / gtt ))) or ( methode von bavel / gtt ))*.