Perhaps you should try some spelling variations:
"world economic and financial systems." » "world economic and financial system.", "world economic and financial statements."
"world economic and financial series." » "world economic and financial services.", "world economic and financial service.", "world economic and financial studies."
"world economy and financial series." » "world economy and financial services.", "world economy and financial service.", "world economy and financial studies."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("world economic and financial systems.") or ((("world economic and financial series.") OR ("world economy and financial series."))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("world economic and financial systems.") OR ((("world economic and financial series.") OR ("world economy and financial series.")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"world economic and financial systems.\") or (((\"world economic and financial series.\") OR (\"world economy and financial series.\"))))".
• Removing quotes may allow a broader search: (( world economic and financial systems. ) or ((( world economic and financial series. ) OR ( world economy and financial series. )))).
• Adding a wildcard symbol may retrieve word variants: (("world economic and financial systems.") or ((("world economic and financial series.") OR ("world economy and financial series."))))*.