Perhaps you should try some spelling variations:
"improving human performance series." » "improving human performance metrics.", "improving human performance reviews.", "improving human performance review.", "improving loan performance series.", "improving thermal performance series.", "improving company performance series.", "improving rural performance series."
"improving urban performance series." » "improving urban performance metrics.", "improving urban performance reviews.", "improving urban performance review.", "improving bank performance series.", "improving loan performance series.", "improving can performance series."

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