Perhaps you should try some spelling variations:
"improving indoor performance series." » "improving outdoor performance series.", "improving poor performance series.", "improving donor performance series.", "improving indoor performance studies.", "improving indoor performance size.", "improving india's performance series.", "improving food performance series.", "improving gender performance series."
"improving rural performance evidence." » "improving euract performance evidence.", "improving larval performance evidence.", "improving pupil 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 rural performance evidence.") or ("improving indoor performance series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving rural performance evidence.") OR ("improving indoor performance series.")).
• Removing quotes may allow a broader search: (( improving rural performance evidence. ) or ( improving indoor performance series. )).
• Adding a wildcard symbol may retrieve word variants: (("improving rural performance evidence.") or ("improving indoor performance series."))*.