Perhaps you should try some spelling variations:
delphi studien » delphi studie, delphi study
filosofia da » filosofia del, filosofia e, filosofia della
filosofia de » filosofia del
test delphi » fast delphi, belts delphi
studien de » studien der, studien die, studien des

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 delphi studien de ((filosofia da) OR (filosofia de)) litterature".
• Adding a wildcard symbol may retrieve word variants: test delphi studien de ((filosofia da) OR (filosofia de)) litterature*.