Perhaps you should try some spelling variations:
"international political economy series" » "international policy economy series", "international political economics series"
"international economics ecological services" » "international economics ecologically services", "international economics technological services", "international economics sociological services", "international economics hydrological services", "international economics clinical services", "international economics meteorological 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 economy series") or ("international economics ecological services"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("international political economy series") OR ("international economics ecological services")).
• Removing quotes may allow a broader search: (( international political economy series ) or ( international economics ecological services )).
• Adding a wildcard symbol may retrieve word variants: (("international political economy series") or ("international economics ecological services"))*.