Perhaps you should try some spelling variations:
"improving city performance series." » "improving city performance metrics.", "improving city performance reviews.", "improving city performance targets.", "improving firm performance series.", "improving high performance series.", "improving key performance series.", "improving its performance series.", "improving equity performance series.", "improving birth performance series."
"improving country performance review." » "improving country performance risk.", "improving country performance evidence.", "improving voluntary performance review.", "importing country performance review.", "borrowing country performance review."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("improving city performance series.") or ("improving country performance review."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving city performance series.") OR ("improving country performance review.")).
• Removing quotes may allow a broader search: (( improving city performance series. ) or ( improving country performance review. )).
• Adding a wildcard symbol may retrieve word variants: (("improving city performance series.") or ("improving country performance review."))*.