Perhaps you should try some spelling variations:
"trubner technik leitfaden" » "trubner methodik leitfaden", "uber technik leitfaden", "struktur technik leitfaden"
"trigger technik leitfaden" » "trigger methodik leitfaden", "trigger mechanism leitfaden"

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"trubner technik leitfaden\") OR (\"trigger technik leitfaden\"))".
• Removing quotes may allow a broader search: (( trubner technik leitfaden ) OR ( trigger technik leitfaden )).
• Adding a wildcard symbol may retrieve word variants: (("trubner technik leitfaden") OR ("trigger technik leitfaden"))*.