Perhaps you should try some spelling variations:
"improving air performance metrics." » "improving air performance contracts.", "improving air performance measures.", "improving air performance contract.", "improving firm performance metrics.", "improving a performance metrics.", "improving ii performance metrics.", "improving water performance metrics.", "improving land performance metrics.", "improving _ performance metrics."
"improving basic performance series." » "improving basic performance reviews.", "improving basic performance review.", "improving basic performance targets.", "improving based performance series.", "improving bank performance series.", "improving past performance series.", "improve basic performance series.", "improving public 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 basic performance series.") or ("improving air performance metrics."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving basic performance series.") OR ("improving air performance metrics."))*.
• Removing quotes may allow a broader search: (( improving basic performance series. ) or ( improving air performance metrics. ))*.