Perhaps you should try some spelling variations:
"international ports economy series" » "international airports economy series", "international poverty economy series", "international efforts economy series", "international forest economy series", "international world economy series", "international host economy series"
"international aids economic studies" » "international aid economic studies", "international air economic studies", "international banks economic studies", "international aids economic status", "international aids economic surveys", "international aids economics studies", "international its economic studies"

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