Perhaps you should try some spelling variations:
pela literatura » pena literatura, la literatura, a literatura
filosofia pela » filosofia della, filosofia del, filosofia para
tests drug » test drug, testing drug, tests during
studie der » studium der
studie de » studie die, studie des, studies de

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 drug ((studie de) OR (studie der)) filosofia pela literatura*.