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 company performance review.", "improving urban performance review.", "improving rural performance review."
"improving power performance series." » "improving power performance metrics.", "improving power performance reviews.", "improving power performance targets.", "improving poor performance series.", "improving worker performance series.", "improving low performance series.", "improving poverty performance series.", "improving water performance series.", "improving upper 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 power performance series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving human performance review.") OR ("improving power performance series.")).
• Removing quotes may allow a broader search: (( improving human performance review. ) or ( improving power performance series. )).
• Adding a wildcard symbol may retrieve word variants: (("improving human performance review.") or ("improving power performance series."))*.