Perhaps you should try some spelling variations:
"improving food performance contract." » "improving food performance contracts.", "improving good performance contract.", "improving fund performance contract.", "improving bond performance contract."
"improving co performance series." » "improving co performance studies.", "improving co performance size.", "improving ceo performance series.", "improving do performance series.", "improving core performance series.", "improving eco performance series.", "improving crop performance series.", "improving ict 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 co performance series.") or ("improving food performance contract."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving co performance series.") OR ("improving food performance contract.")).
• Removing quotes may allow a broader search: (( improving co performance series. ) or ( improving food performance contract. )).
• Adding a wildcard symbol may retrieve word variants: (("improving co performance series.") or ("improving food performance contract."))*.