Perhaps you should try some spelling variations:
a literatura » la literatura, a literature, y literatura
tests acute » testis acute, testing acute, versus acute
filosofia a » filosofia da, filosofia la, filosofia e
studien dd » studien der, studien die, studien des
studies dd » studies ds, studies d, studies dn

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: "tests acute ((studien dd) OR (studies dd)) filosofia a literatura*".