Perhaps you should try some spelling variations:
grobner methodischer » probleme methodischer, erster methodischer, oder methodischer
technik leitfaden » methodik leitfaden
trubner technik » uber technik, trigger technik, struktur technik

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: (( trubner technik leitfaden ) OR ( grobner methodischer leitfaden )).
• Adding a wildcard symbol may retrieve word variants: (( trubner technik leitfaden ) or ( grobner methodischer leitfaden ))*.