Perhaps you should try some spelling variations:
testing drugs » testing drug, existing drugs, acting drugs
drugs studied » drugs studies, drug studies, groups studied
e filosofiche » ve filosoficke, e filosofica, e filosofie
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: testing drugs studied ((e filosofiche) OR (e filosofia)) e literatur.
• Adding a wildcard symbol may retrieve word variants: testing drugs studied ((e filosofiche) or (e filosofia)) e literatur*.