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 co performance risk." » "improving co performance 2019.", "improving ceo performance risk.", "improving do performance risk.", "improving core performance risk.", "improving eco performance risk.", "improving crop performance risk.", "improving ict performance risk."

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

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