Perhaps you should try some spelling variations:
der filosofia » de filosofia, e filosofia, di filosofia
la literatura » la litterature, a literature
filosofia la » filosofia da, filosofia le, filosofica da
test delphi » belts delphi
studien der » studie der, studien die, studenten 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) OR (fast delphi)) studien der filosofia la literatura".
• Adding a wildcard symbol may retrieve word variants: ((test delphi) OR (fast delphi)) studien der filosofia la literatura*.