Perhaps you should try some spelling variations:
"international policy economy theories" » "international poverty economy theories", "international prices economy theories", "international policy economics theories", "international policy economy series", "international policy economy theory", "international polish economy theories", "international politics economy theories"
"national policy economic theories" » "national policy economic theory", "national policy economics series", "national poverty economic theories"

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

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