Perhaps you should try some spelling variations:
"improving crop performance series." » "improving crop performance metrics.", "improving crop performance reviews.", "improving crop performance review.", "improving poor performance series.", "improving job performance series.", "improving city performance series.", "improving co performance series.", "improving macro performance series.", "improving food performance series."
"improving urban performance risks." » "improving bank performance risks.", "improving loan performance risks.", "improving can performance risks.", "improving urban performance risk.", "improving urban performance issues.", "improving urban performance based."

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