Perhaps you should try some spelling variations:
drugs studies » drug studies
1 filosofica » e filosofica, a filosofia, y filosofia
drug studie » drug studies, drugs studied, drug study
e filosofia » la filosofia
literatur » literature

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: tests ((drug studie) OR (drugs studies)) ((1 filosofica) OR (e filosofia)) e literatur.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tests ((drug studie) OR (drugs studies)) ((1 filosofica) or (e filosofia)) e literatur".
• Adding a wildcard symbol may retrieve word variants: tests ((drug studie) OR (drugs studies)) ((1 filosofica) or (e filosofia)) e literatur*.