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
tests drug » test drug, testing drug, tests during

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