Perhaps you should try some spelling variations:
"trubner methodik leitfaden" » "trubner technik leitfaden", "trubner methodischer leitfaden", "uber methodik leitfaden", "einer methodik leitfaden", "leber methodik leitfaden"
"grobner methods leitfaden" » "grobner methode leitfaden", "grobner methodischer leitfaden", "grobner rechts leitfaden", "greener methods leitfaden", "proper methods leitfaden", "frontier methods 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 methodik leitfaden\") OR (\"grobner methods leitfaden\"))".
• Removing quotes may allow a broader search: (( trubner methodik leitfaden ) OR ( grobner methods leitfaden )).
• Adding a wildcard symbol may retrieve word variants: (("trubner methodik leitfaden") OR ("grobner methods leitfaden"))*.