Perhaps you should try some spelling variations:
"international policy economic surveys" » "international poverty economic surveys", "international prices economic surveys", "national policy economic surveys", "international policy economic studies", "international policy economic systems"
"international treaty economic services" » "international treaties economic services", "international trade economic services", "international trends economic services", "international treaty economics series", "international treaty ecological services", "international treaty economic studies", "international create economic services", "international great economic services", "international greater economic services"

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("international policy economic surveys") or ("international treaty economic services"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("international policy economic surveys") OR ("international treaty economic services"))*.
• Removing quotes may allow a broader search: (( international policy economic surveys ) or ( international treaty economic services ))*.