Perhaps you should try some spelling variations:
"improving urban performance series." » "improving urban performance studies.", "improving urban performance size.", "improving bank performance series.", "improving loan performance series.", "improving human performance series."
"improving local performance series." » "improving local performance studies.", "improving local performance size.", "improving social performance series.", "improving global performance series.", "improving total performance series.", "improving fiscal performance series."

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

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