Perhaps you should try some spelling variations:
"improving country performance contract." » "improving country performance contracts.", "improving voluntary performance contract.", "importing country performance contract.", "improving community performance contract."
"improving maternal performance metrics." » "improving materials performance metrics.", "improving external performance metrics.", "improving national performance metrics.", "improving maternal performance measures.", "improve maternal performance metrics.", "improving water performance metrics."

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("improving country performance contract.") or ("improving maternal performance metrics."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving country performance contract.") OR ("improving maternal performance metrics.")).
• Removing quotes may allow a broader search: (( improving country performance contract. ) or ( improving maternal performance metrics. )).
• Adding a wildcard symbol may retrieve word variants: (("improving country performance contract.") or ("improving maternal performance metrics."))*.