Perhaps you should try some spelling variations:
"improving co performance metrics." » "improving co performance measures.", "improving ceo performance metrics.", "improving do performance metrics.", "improving core performance metrics.", "improving eco performance metrics.", "improving crop performance metrics.", "improving ict performance metrics."
"improving trade performance series." » "improving trade performance studies.", "improving trade performance size.", "improving care performance series.", "improving tax performance series.", "improving teacher 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 trade performance series.") OR ("improving co performance metrics."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"improving trade performance series.\") OR (\"improving co performance metrics.\"))".
• Removing quotes may allow a broader search: (( improving trade performance series. ) OR ( improving co performance metrics. )).
• Adding a wildcard symbol may retrieve word variants: (("improving trade performance series.") OR ("improving co performance metrics."))*.