Perhaps you should try some spelling variations:
delphi studien » delphi studie, delphi study
die filosofia » di filosofia, de filosofia, e filosofia
de literatura » de litterature, la literatura, a literatura
y literatura » la literatura
test delphi » fast delphi, belts delphi
studien die » studie die, studien der

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