Perhaps you should try some spelling variations:
"international policy economics series" » "international poverty economics series", "international prices economics series", "national policy economics series", "international policy economic series", "international politics economics series", "international politik economics series"
"international energy economic series" » "international energy economics series", "international energy economy series", "international ecology economic series", "international energy economic services", "international energy 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 policy economics series") or ("international energy economic series"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("international policy economics series") OR ("international energy economic series")).
• Removing quotes may allow a broader search: (( international policy economics series ) or ( international energy economic series )).
• Adding a wildcard symbol may retrieve word variants: (("international policy economics series") or ("international energy economic series"))*.