Perhaps you should try some spelling variations:
"improving firm performance risks." » "improving firm performance risk.", "improving firm performance issues.", "improving firm performance based.", "improving _ performance risks.", "improving firms performance risks.", "improving air performance risks.", "improving birth performance risks."
"improving human performance evidence." » "improving loan performance evidence.", "improving thermal performance evidence.", "improving company performance evidence.", "improving urban performance evidence.", "improving rural performance evidence."

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

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