Perhaps you should try some spelling variations:
"international policy economy series" » "international poverty economy series", "international prices economy series", "national policy economy series", "international policy economic series", "international polish economy series", "international politics economy series", "international policy economics series"
"international economics ecological studies" » "international economics ecologically studies", "international economics technological studies", "international economics sociological studies", "international economics ecological services", "international economics archaeological studies"

Try widening your search to All Fields.

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