Perhaps you should try some spelling variations:
"improving federal performance series." » "improving general performance series.", "improving senegal performance series.", "improving sectoral performance series.", "improving federal performance studies.", "improving federal performance size.", "improve federal performance series.", "improving central performance series.", "improving neural performance series."
"improving animal performance review." » "improving annual performance review.", "improving thermal performance review.", "improving fiscal performance review.", "improving animal performance risk.", "improving animal performance evidence.", "improving initial performance review.", "improving optimal performance review.", "improving criminal performance review."

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