Perhaps you should try some spelling variations:
"improving rural performance series." » "improving rural performance studies.", "improving rural performance size.", "improving euract performance series.", "improving larval performance series.", "improving pupil performance series."
"improving supply performance contracts." » "improving support performance contracts.", "improving safety performance contracts.", "improving turkey performance contracts.", "improving early performance contracts.", "improving skills performance contracts."

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