Perhaps you should try some spelling variations:
di literatura » de literatura, da literatura, ii literatura
filosofia di » filosofia de, filosofia da, filosofia del
tests safe » tests safety, tests scale, tests space
studien am » studien aus, studien auf, studien _
studien a » studien _, studien 3, studien 4

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: tests safe ((studien a) OR (studien am)) filosofia di literatura*.