Perhaps you should try some spelling variations:
"national poverty economic surveys" » "national property economic surveys", "national forestry economic surveys", "national policy economic surveys", "national poverty economic studies", "national poverty economic systems"
"international prices economic series" » "international crises economic series", "international prices econometric series", "international services economic series", "international prices economics series", "international prices economic services", "international prices economy 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 prices economic series") or ("national poverty economic surveys"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("international prices economic series") OR ("national poverty economic surveys")).
• Removing quotes may allow a broader search: (( international prices economic series ) or ( national poverty economic surveys )).
• Adding a wildcard symbol may retrieve word variants: (("international prices economic series") or ("national poverty economic surveys"))*.