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 land performance series." » "improving land performance studies.", "improving land performance size.", "improving plant performance series.", "improving fund performance series.", "improving und 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 land performance series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving multi performance metrics.") OR ("improving land performance series.")).
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