Perhaps you should try some spelling variations:
"improving contract performance contract." » "improving country performance contract.", "improving court performance contract.", "improving economic performance contract.", "improving contract performance contracts.", "improve contract performance contract.", "improving central performance contract.", "improve contrast performance contract."
"improving care performance series." » "improving care performance studies.", "improving care performance size.", "improving trade performance series.", "improving drive performance series.", "improving 2 performance series.", "improving early performance series.", "improving air performance series.", "improving data 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 contract performance contract.") or ("improving care performance series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving contract performance contract.") OR ("improving care performance series.")).
• Removing quotes may allow a broader search: (( improving contract performance contract. ) or ( improving care performance series. )).
• Adding a wildcard symbol may retrieve word variants: (("improving contract performance contract.") or ("improving care performance series."))*.