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