Perhaps you should try some spelling variations:
drugs studied » drugs studies, drug studies, groups studied
filosofico e » filosofica e, filosofici e, filosoficas de
tests drugs » tests drug, test drugs, testing drugs
filosofia e » filosofia de, filosofia del
studied y » studied _, studied 3, studied 5

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 drugs studied y ((filosofico e) OR (filosofia e)) literatura*".