Perhaps you should try some spelling variations:
"improving basic performance measures." » "improving based performance measures.", "improving music performance measures.", "improving baseline performance measures.", "improving air performance measures.", "improve basic performance measures."
"improving past performance based." » "improving plant performance based.", "improving port performance based.", "improving transit performance based.", "improving fast performance based.", "improving post performance based."

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