Perhaps you should try some spelling variations:
"improving basic performance contract." » "improving basic performance contracts.", "improving based performance contract.", "improving bank performance contract.", "improving past performance contract.", "improving air performance contract.", "improve basic performance contract.", "improving public performance contract."
"improving care performance based." » "improving care performance measures.", "improving market performance based.", "improving trade performance based.", "improving court performance based.", "improving water performance based.", "improving early performance based.", "improving land performance based."

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