Perhaps you should try some spelling variations:
"international political ecological services" » "international policy ecological services", "international political technological services", "international political ecologies services", "international political economic services", "international political hydrological services", "international political clinical services", "international political meteorological services"
"national policy economic series" » "national poverty economic series", "national policy economics series", "national policy economic services", "national policy economy series"

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