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

Try widening your search to All Fields.

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• Performing a fuzzy search may retrieve terms with similar spellings: (("international policy economic studies") or ("international policy economic theories"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("international policy economic studies") OR ("international policy economic theories")).
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