Perhaps you should try some spelling variations:
"improving past performance series." » "improving past performance studies.", "improving past performance size.", "improving plant performance series.", "improving port performance series.", "improving transit performance series.", "improving fast performance series.", "improving post performance series."
"improving based performance standards." » "improving board performance standards.", "improving fund performance standards.", "improving good performance standards.", "improving basic performance standards.", "improving care performance standards.", "improving asset performance standards."

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("improving based performance standards.") or ("improving past performance series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving based performance standards.") OR ("improving past performance series.")).
• Removing quotes may allow a broader search: (( improving based performance standards. ) or ( improving past performance series. )).
• Adding a wildcard symbol may retrieve word variants: (("improving based performance standards.") or ("improving past performance series."))*.