Perhaps you should try some spelling variations:
della letteratura » nella letteratura, e letteratura
filosofia della » filosofia del, filosofia de
der filosofia » de filosofia, e filosofia, di filosofia
tests drug » testing drug, tests during
studie der » studium der
test drug » best drugs, test du, fast drug

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 drug) OR (test drug)) studie der filosofia della letteratura*".