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