Perhaps you should try some spelling variations:
technik leitfaden » methodik leitfaden
trubner methodik » uber methodik, einer methodik, leber methodik
trubner technik » uber technik, trigger technik, struktur technik
grobner methods » greener methods, proper methods, frontier methods

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 ( ((trubner methodik) OR (grobner methods)) leitfaden )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( trubner technik leitfaden ) or ( ((trubner methodik) OR (grobner methods)) leitfaden ))".
• Adding a wildcard symbol may retrieve word variants: (( trubner technik leitfaden ) or ( ((trubner methodik) OR (grobner methods)) leitfaden ))*.