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 economics series", "international political ecological services", "international political economic studies"
"national policy economic series" » "national poverty economic series", "national policy economics series", "national policy economy series", "national policy economic theories"

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