Perhaps you should try some spelling variations:
"improving can performance series." » "improving can performance studies.", "improving can performance size.", "improving chain performance series.", "improving loan performance series.", "improving human performance series.", "improving care performance series.", "improving a performance series.", "improving co performance series."
"improving macro performance series." » "improving macro performance studies.", "improving macro performance size.", "improving crop performance series.", "improving ceo performance series.", "improving machine performance series.", "improving air performance series.", "improving care performance series.", "improving co performance series."

Try widening your search to All Fields.

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