Perhaps you should try some spelling variations:
"improving pupil performance series." » "improving pupil performance studies.", "improving pupil performance size.", "improving social performance series.", "improving model performance series.", "improving judicial performance series.", "improving public performance series.", "improving audit performance series.", "improving fuel performance series."
"improving civil performance series." » "improving civil performance studies.", "improving civil performance size.", "improving level performance series.", "improving driving performance series.", "improving initial performance series.", "improving civic performance series.", "improving living performance series.", "improving child 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 pupil performance series.") OR ("improving civil performance series."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"improving pupil performance series.\") OR (\"improving civil performance series.\"))".
• Removing quotes may allow a broader search: (( improving pupil performance series. ) OR ( improving civil performance series. )).
• Adding a wildcard symbol may retrieve word variants: (("improving pupil performance series.") OR ("improving civil performance series."))*.