Perhaps you should try some spelling variations:
"improving human performance review." » "improving human performance risk.", "improving human performance evidence.", "improving loan performance review.", "improving thermal performance review.", "improving chain performance review."
"improving upper performance series." » "improving upper performance studies.", "improving upper performance size.", "improving under performance series.", "improving support performance series.", "improving capped performance series.", "improving supply performance series.", "improving budget performance series.", "improving gender 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 human performance review.") or ("improving upper performance series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving human performance review.") OR ("improving upper performance series.")).
• Removing quotes may allow a broader search: (( improving human performance review. ) or ( improving upper performance series. )).
• Adding a wildcard symbol may retrieve word variants: (("improving human performance review.") or ("improving upper performance series."))*.