Perhaps you should try some spelling variations:
de literature » de litterature, de lite'rature, de literatura
filosofia de » filosofia del
studien a » studien am, studien _, studien 4
studien 3 » studien _, studien 4, studien 5
test » text

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: test (doubles OR troubles) ((studien a) OR (studien 3)) filosofia de literature.
• The words AND, OR and NOT may confuse the search; try adding quotes: "test (doubles or troubles) ((studien a) OR (studien 3)) filosofia de literature".
• Adding a wildcard symbol may retrieve word variants: test (doubles or troubles) ((studien a) OR (studien 3)) filosofia de literature*.