Perhaps you should try some spelling variations:
"international policy economic theories" » "international poverty economic theories", "international prices economic theories", "national policy economic theories", "international policy economic theory", "international policy economics series"
"international policy ecological services" » "international poverty ecological services", "international prices ecological services", "national policy ecological services", "international policy hydrological services", "international policy clinical services", "international policy meteorological services", "international policy psychological services", "international social ecological services", "international socio ecological services"

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("international policy economic theories") or ("international policy ecological services"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("international policy economic theories") OR ("international policy ecological services")).
• Removing quotes may allow a broader search: (( international policy economic theories ) or ( international policy ecological services )).
• Adding a wildcard symbol may retrieve word variants: (("international policy economic theories") or ("international policy ecological services"))*.