Perhaps you should try some spelling variations:
"international aid economic services" » "international airshow economic services", "international airport economic services", "international aid economics series", "international aid ecological services", "international aid economic studies", "international rapid economic services", "international aids economics services", "international avoid economic services"
"international prices economic theories" » "international prices economic theory", "international prices economics series", "international crises economic theories", "international prices econometric theories", "international services economic theories"

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 ("international aid economic services"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("international prices economic theories") OR ("international aid economic services")).
• Removing quotes may allow a broader search: (( international prices economic theories ) or ( international aid economic services )).
• Adding a wildcard symbol may retrieve word variants: (("international prices economic theories") or ("international aid economic services"))*.