Perhaps you should try some spelling variations:
"international ports economy series" » "international airports economy series", "international poverty economy series", "international efforts economy series", "international ports economics series", "international porn economy series", "international sports economic series", "international export economy series"
"international aids economic surveys" » "international aid economic surveys", "international air economic surveys", "international airshow economic surveys", "international aids economic studies", "international aids economic systems", "international aids economics surveys", "international sands economic surveys"

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

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