Perhaps you should try some spelling variations:
della letteratura » nella letteratura
e letteratura » y literatura, e literatur
drug studie » drug studies, drugs studies, drugs studied
e filosofia » la filosofia
tests drug » test drug, testing drug, tests during
studie e » studie 2, studie _, studie 1

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 e filosofia ((della letteratura) OR (e letteratura))*".