Perhaps you should try some spelling variations:
"Improving human performance metrics." » "Improving human performance contracts.", "Improving human performance measures.", "Improving human performance contract.", "Improving loan performance metrics.", "Improving company performance metrics.", "Improving animal performance metrics."
"improving thermal performance series." » "improving thermal performance reviews.", "improving thermal performance review.", "improving thermal performance targets.", "improving maternal performance series.", "improving rural performance series.", "improving mental performance series."
improving human » improving urban, improving rural

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 metrics.") or ("improving thermal performance series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("Improving human performance metrics.") OR ("improving thermal performance series."))*.
• Removing quotes may allow a broader search: (( Improving human performance metrics. ) or ( improving thermal performance series. ))*.