Perhaps you should try some spelling variations:
"improving bank performance series." » "improving bank performance studies.", "improving bank performance size.", "improving urban performance series.", "improving basic performance series.", "improving brain performance series."
"improving crop performance evidence." » "improving group performance evidence.", "improving top performance evidence.", "improving do performance evidence.", "improving co performance evidence.", "improving pro performance evidence.", "improving macro performance evidence."

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

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