Perhaps you should try some spelling variations:
stable studenten » table student, schuler studenten, enable students
der filosofia » de filosofia, e filosofia, da filosofia
de literatura » de litterature, la literatura, y literatura
tests stable » tests table, sets stable, test table
di filosofia » la filosofia, e filosofia

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: "tests stable studenten ((der filosofia) OR (di filosofia)) de literatura".
• Adding a wildcard symbol may retrieve word variants: tests stable studenten ((der filosofia) OR (di filosofia)) de literatura*.