Perhaps you should try some spelling variations:
da literature » a literature, da literatura, la literature
tests stable » tests table, test table, tests scale
filosofia da » filosofia de, filosofia del, filosofia e
sets stable » sets table, setup stable, sets state

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 stable) OR (sets stable)) studien _ filosofia da literature.
• Adding a wildcard symbol may retrieve word variants: ((tests stable) or (sets stable)) studien _ filosofia da literature*.