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 poor performance series." » "improving poor performance studies.", "improving poor performance size.", "improving sector performance series.", "improving power performance series.", "improving food performance series.", "improving peer 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 poor performance series."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"improving human performance review.\") OR (\"improving poor performance series.\"))*".
• Removing quotes may allow a broader search: (( improving human performance review. ) OR ( improving poor performance series. ))*.