Perhaps you should try some spelling variations:
pela literatura » pena literatura, la literatura, a literatura
der filosofia » de filosofia, di filosofia, da filosofia
drug studie » drug studies, drugs studies, drugs studied
e filosofia » la filosofia
test drug » tests drug, best drugs, test du

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 drug studie ((der filosofia) OR (e filosofia)) pela literatura.
• Adding a wildcard symbol may retrieve word variants: test drug studie ((der filosofia) or (e filosofia)) pela literatura*.