Perhaps you should try some spelling variations:
"improving food performance series." » "improving food performance metrics.", "improving food performance reviews.", "improving food performance review.", "improving good performance series.", "improving poor performance series.", "improving fund performance series.", "improving land performance series."
"improving human performance evidence." » "improving loan performance evidence.", "improving thermal performance evidence.", "improving company performance evidence.", "improving urban performance evidence.", "improving rural 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 human performance evidence.") or ("improving food performance series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving human performance evidence.") OR ("improving food performance series.")).
• Removing quotes may allow a broader search: (( improving human performance evidence. ) or ( improving food performance series. )).
• Adding a wildcard symbol may retrieve word variants: (("improving human performance evidence.") or ("improving food performance series."))*.