Perhaps you should try some spelling variations:
"improving contract performance evidence." » "improving country performance evidence.", "improving court performance evidence.", "improving economic performance evidence.", "improve contract performance evidence.", "improving central performance evidence.", "improve contrast performance evidence."
"improving rural performance series." » "improving rural performance studies.", "improving rural performance size.", "improving euract performance series.", "improving larval performance series.", "improving pupil 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 contract performance evidence.") or ("improving rural performance series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving contract performance evidence.") OR ("improving rural performance series.")).
• Removing quotes may allow a broader search: (( improving contract performance evidence. ) or ( improving rural performance series. )).
• Adding a wildcard symbol may retrieve word variants: (("improving contract performance evidence.") or ("improving rural performance series."))*.