Perhaps you should try some spelling variations:
"world bank regional and sectoral studies" » "world bank regional and sectional studies", "world bank regional and spectral studies", "world bank regional and sector studies", "world lanka regional and sectoral studies", "world mask regional and sectoral studies", "world park regional and sectoral studies"
"World Bank regional and doctoral studies" » "World Bank regional and doctoral student", "World Bank regional and cultural studies", "World Bank regional and spectral studies"

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: (("world bank regional and sectoral studies") OR ((("World Bank regional and doctoral studies") OR ("World Bank regional and doctoral students")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"world bank regional and sectoral studies\") or (((\"World Bank regional and doctoral studies\") OR (\"World Bank regional and doctoral students\"))))".
• Removing quotes may allow a broader search: (( world bank regional and sectoral studies ) or ((( World Bank regional and doctoral studies ) OR ( World Bank regional and doctoral students )))).
• Adding a wildcard symbol may retrieve word variants: (("world bank regional and sectoral studies") or ((("World Bank regional and doctoral studies") OR ("World Bank regional and doctoral students"))))*.