Perhaps you should try some spelling variations:
"improving mental performance measures." » "improving general performance measures.", "improving senegal performance measures.", "improving annual performance measures.", "improving maternal performance measures.", "improving fiscal performance measures.", "improving gender performance measures."
"improving human performance risks." » "improving loan performance risks.", "improving thermal performance risks.", "improving chain performance risks.", "improving human performance risk."

Try widening your search to All Fields.

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

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