Perhaps you should try some spelling variations:
spaces studied » species studied, space studies, states studied
duale studium » duales studium, dualen studium, das studium
di filosofia » la filosofia, e filosofia
filosofia a » filosofia da, filosofia la, filosofia e

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 ((duale studium) OR (spaces studied)) di filosofia a literature.
• Adding a wildcard symbol may retrieve word variants: tests ((duale studium) or (spaces studied)) di filosofia a literature*.