Perhaps you should try some spelling variations:
de literatura » de litterature, la literatura, y literatura
filologia de » filologia e, fisiologia de, filosofia de
test duale » test double, test delle, test orale
studien es » studien aus, studien bei, studien ein
studien e » studien _, studien 3, studien 4

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: "test duale ((studien e) OR (studien es)) filologia de literatura".
• Adding a wildcard symbol may retrieve word variants: test duale ((studien e) OR (studien es)) filologia de literatura*.