Perhaps you should try some spelling variations:
suitable studies » table studies, unstable studies, suitability studies
de literatura » de litterature, la literatura, y literatura
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.

• The words AND, OR and NOT may confuse the search; try adding quotes: "most suitable studies ((de filosofia) OR (di filosofia)) de literatura".
• Adding a wildcard symbol may retrieve word variants: most suitable studies ((de filosofia) OR (di filosofia)) de literatura*.