Perhaps you should try some spelling variations:
"international political economic services" » "international policy economic services", "international political economy services", "international ecological economics services", "international political ecological services", "international political economic surveys", "international political economic studies"
"international energy economics services" » "international best economics services", "international energy ecological services", "international energy economics studies", "international energy economicshealth services"

Try widening your search to All Fields.

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

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