Perhaps you should try some spelling variations:
der filosofia » de filosofia, e filosofia, di filosofia
a literatura » la literatura, a literature, y literatura
a literatur » a literature
tests das » tests des, test das, tests data

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: tests das studium der filosofia ((((a literatura) OR (a literatur))) OR (l((a literatura) OR (a literatur)))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tests das studium der filosofia ((((a literatura) OR (a literatur))) or (l((a literatura) OR (a literatur))))".
• Adding a wildcard symbol may retrieve word variants: tests das studium der filosofia ((((a literatura) OR (a literatur))) or (l((a literatura) OR (a literatur))))*.