Perhaps you should try some spelling variations:
"improving food performance contract." » "improving food performance contracts.", "improving good performance contract.", "improving poor performance contract.", "improving fund performance contract.", "improving land performance contract."
"improving human performance series." » "improving human performance metrics.", "improving human performance reviews.", "improving human performance review.", "improving loan performance series.", "improving thermal performance series.", "improving company performance series.", "improving urban performance series.", "improving rural performance series."

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 series.") or ("improving food performance contract."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving human performance series.") OR ("improving food performance contract."))*.
• Removing quotes may allow a broader search: (( improving human performance series. ) or ( improving food performance contract. ))*.