Perhaps you should try some spelling variations:
"improving multi performance metrics." » "improving multi performance measures.", "improving multiple performance metrics.", "improving mpi performance metrics.", "improving results performance metrics.", "improving adult performance metrics.", "improving culture performance metrics."
"improving lead performance series." » "improving lead performance studies.", "improving lead performance size.", "improving end performance series.", "improving esd performance series.", "improving reward performance series.", "improving legal performance series.", "improving land performance series.", "improving eap performance series."

Try widening your search to All Fields.

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• Performing a fuzzy search may retrieve terms with similar spellings: (("improving multi performance metrics.") or ("improving lead performance series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving multi performance metrics.") OR ("improving lead performance series.")).
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