Perhaps you should try some spelling variations:
della letteratura » nella letteratura, e letteratura
filosofia della » filosofia del, filosofia de
e filosofia » la filosofia
zu studien » zu studie, zu studieren, wozu studien
du studie » zu studie, eu studies, du studierst

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: "test ((du studie) OR (zu studien)) e filosofia della letteratura*".