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 poor performance series." » "improving poor performance studies.", "improving poor performance size.", "improving sector performance series.", "improving power performance series.", "improving food performance series.", "improving peer 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 contract performance contract.") or ("improving poor performance series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving contract performance contract.") OR ("improving poor performance series.")).
• Removing quotes may allow a broader search: (( improving contract performance contract. ) or ( improving poor performance series. )).
• Adding a wildcard symbol may retrieve word variants: (("improving contract performance contract.") or ("improving poor performance series."))*.