Perhaps you should try some spelling variations:
"international forest economic studies" » "international forestry economic studies", "international best economic studies", "international firms economic studies", "international forest economic status", "international forest economics studies", "international forest economy studies"
"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"

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

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