Perhaps you should try some spelling variations:
stable studien » stadler studien, scale studien, table studies
la literatura » la litterature, a literature
tests stable » tests table, sets stable, test table
de filosofia » e filosofia, la filosofia, a filosofia
di filosofia » la filosofia, e filosofia

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 studien ((de filosofia) OR (di filosofia)) la literatura.
• Adding a wildcard symbol may retrieve word variants: tests stable studien ((de filosofia) or (di filosofia)) la literatura*.