Perhaps you should try some spelling variations:
"improving quality performance series." » "improving utility performance series.", "improving safety performance series.", "improving city performance series.", "improving quality performance metrics.", "improving quality performance reviews.", "improving quality performance review.", "improving health performance series."
"improving past performance risk." » "improving plant performance risk.", "improving port performance risk.", "improving based performance risk.", "improving past performance size.", "improving past performance based.", "improving past performance _.", "improving basic performance risk.", "improving asset performance risk.", "improving land performance risk."

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