Perhaps you should try some spelling variations:
"improving maternal performance contract." » "improving national performance contract.", "improving thermal performance contract.", "improving lanterns performance contract.", "improving maternal performance contracts.", "improve maternal performance contract.", "improving water performance contract."
"improving country performance metrics." » "improving country performance contracts.", "improving country performance measures.", "improving voluntary performance metrics.", "importing country performance metrics.", "borrowing country 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 metrics.") or ("improving maternal performance contract."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving country performance metrics.") OR ("improving maternal performance contract.")).
• Removing quotes may allow a broader search: (( improving country performance metrics. ) or ( improving maternal performance contract. )).
• Adding a wildcard symbol may retrieve word variants: (("improving country performance metrics.") or ("improving maternal performance contract."))*.