Perhaps you should try some spelling variations:
del literatura » de literatura, pela literatura, da literatura
drugs studies » drug studies
der filosofia » e filosofia, di filosofia, da filosofia
de filosofia » e filosofia, di filosofia, la filosofia
best drugs » obesity drugs

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: "best drugs studies ((der filosofia) OR (de filosofia)) del literatura".
• Adding a wildcard symbol may retrieve word variants: best drugs studies ((der filosofia) OR (de filosofia)) del literatura*.