Perhaps you should try some spelling variations:
"improving country performance series." » "improving country performance studies.", "improving country performance size.", "improving voluntary performance series.", "importing country performance series.", "improving community performance series."
"improving company performance evidence." » "improve company performance evidence.", "improving compliance performance evidence.", "improving community performance evidence."

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 series.") OR ("improving company performance evidence."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"improving country performance series.\") OR (\"improving company performance evidence.\"))".
• Removing quotes may allow a broader search: (( improving country performance series. ) OR ( improving company performance evidence. )).
• Adding a wildcard symbol may retrieve word variants: (("improving country performance series.") OR ("improving company performance evidence."))*.