Perhaps you should try some spelling variations:
"international prices economic theories" » "international prices economic theory", "international prices economics series", "international crises economic theories", "international prices econometric theories", "international services economic theories"
"national poverty economic status" » "national property economic status", "national forestry economic status", "national policy economic status", "national poverty economic sectors", "national poverty socioeconomic status"

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 theories") OR ("national poverty economic status"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"international prices economic theories\") OR (\"national poverty economic status\"))".
• Removing quotes may allow a broader search: (( international prices economic theories ) OR ( national poverty economic status )).
• Adding a wildcard symbol may retrieve word variants: (("international prices economic theories") OR ("national poverty economic status"))*.