Perhaps you should try some spelling variations:
da literatura » la literatura, a literatura, de literatura
filosofia da » filosofia de, filosofia del, filosofia e
studien a » studien am, studien _, studien 4
studien 3 » studien _, studien 4, studien 5
test zu » test zur, tests zu, test zum

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 zu ((studien a) OR (studien 3)) filosofia da literatura.
• Adding a wildcard symbol may retrieve word variants: test zu ((studien a) or (studien 3)) filosofia da literatura*.