Perhaps you should try some spelling variations:
"international river economic studies" » "international water economic studies", "international air economic studies", "international poverty economic studies", "international river economic status", "international river economic surveys", "international driven economic studies", "international wider economic studies", "international drive economic studies"
"international rice economic studies" » "international price economic studies", "international prices economic studies", "international aid economic studies", "international rice economic status", "international rice economic surveys", "international drive economic studies", "international nile economic studies", "international rate economic studies"

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

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