Perhaps you should try some spelling variations:
"improving voluntary performance risk." » "improving country performance risk.", "improving entry performance risk.", "improving industry performance risk.", "improving voluntary performance 2019."
"improving its performance review." » "improving its performance evidence.", "improving items performance review.", "improving units performance review.", "improving als performance review.", "improving city performance review.", "improving eitc performance review.", "improving isps performance review."

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

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