Perhaps you should try some spelling variations:
filosofia vii » filosofia di, filosofia del, filosofia de
vii literatur » viii literatur, vi literatur, ii literatur
studien der » studie der, studenten der
tests safe » tests safety, tests scale, tests space
studien de » studien die, studien des, studien dd

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 de) OR (studien der)) filosofia vii literatur*.