Perhaps you should try some spelling variations:
"improving maternal performance risk." » "improving national performance risk.", "improving thermal performance risk.", "improving lanterns performance risk.", "improve maternal performance risk.", "improving water performance risk.", "improving maternal performance size.", "improving maternal performance based.", "improving maternal performance _."
"improving company performance reviews." » "improving country performance reviews.", "improving loan performance reviews.", "improving corporate performance reviews.", "improving company performance review.", "improving company performance reports.", "improving company performance risks.", "improving human performance reviews."

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

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