Perhaps you should try some spelling variations:
economic rationale » economics regional, economies national
economic aziendale » economico aziendale, economia aziendale, economic agenda
recherche basis » recherche mais, rechtliche basis, recherche dans
de recherche » la recherche
studi de » studi di, studi e, studie der

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: studi de recherche basis ((economic aziendale) OR (economic rationale)) ;~.
• Adding a wildcard symbol may retrieve word variants: studi de recherche basis ((economic aziendale) or (economic rationale)) ;*.