Perhaps you should try some spelling variations:
"improving urban performance review." » "improving urban performance risk.", "improving urban performance evidence.", "improving bank performance review.", "improving loan performance review.", "improving human performance review."
"improving mental performance series." » "improving general performance series.", "improving senegal performance series.", "improving annual performance series.", "improving mental performance studies.", "improving mental performance size.", "improving maternal performance series.", "improving fiscal performance series.", "improving gender performance series."

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

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