Perhaps you should try some spelling variations:
"importing country performance series." » "importing country performance studies.", "importing country performance size.", "important country performance series.", "reporting country performance series.", "exporting country performance series."
"improving poor performance series." » "improving poor performance studies.", "improving poor performance size.", "improving sector performance series.", "improving power performance series.", "improving food performance series.", "improving peer 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: (("importing country performance series.") OR ("improving poor performance series."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"importing country performance series.\") OR (\"improving poor performance series.\"))".
• Removing quotes may allow a broader search: (( importing country performance series. ) OR ( improving poor performance series. )).
• Adding a wildcard symbol may retrieve word variants: (("importing country performance series.") OR ("improving poor performance series."))*.