Perhaps you should try some spelling variations:
a litterature » la litterature, _ litterature, et litterature
studium das » studium des, studium der, studium die
studium da » studium a, studium d, studium der
test des » test der, test test

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 des ((studium da) OR (studium das)) filosofia ((a litterature) OR (a literature)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "test des ((studium da) or (studium das)) filosofia ((a litterature) OR (a literature))".
• Adding a wildcard symbol may retrieve word variants: test des ((studium da) or (studium das)) filosofia ((a litterature) OR (a literature))*.