Perhaps you should try some spelling variations:
"international efforts economics series" » "international airports economics series", "international energy economics series", "international airport economics series", "international effects economics series", "international sports economic series", "international forest economics series"
"international scope economy series" » "international scale economy series", "international school economy series", "international ship economy series", "international income economy series", "international second economy series", "international open economy series"

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("international scope economy series") OR ("international efforts economics series"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"international scope economy series\") OR (\"international efforts economics series\"))".
• Removing quotes may allow a broader search: (( international scope economy series ) OR ( international efforts economics series )).
• Adding a wildcard symbol may retrieve word variants: (("international scope economy series") OR ("international efforts economics series"))*.