Perhaps you should try some spelling variations:
"borrowing country performance series." » "borrowing country performance studies.", "borrowing country performance size.", "borrowing countries performance series.", "borrowing costs performance series.", "borrowing cost performance series."
"improving human performance review." » "improving human performance risk.", "improving human performance evidence.", "improving loan performance review.", "improving thermal performance review.", "improving chain performance review."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("borrowing country performance series.") OR ("improving human performance review."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"borrowing country performance series.\") OR (\"improving human performance review.\"))".
• Removing quotes may allow a broader search: (( borrowing country performance series. ) OR ( improving human performance review. )).
• Adding a wildcard symbol may retrieve word variants: (("borrowing country performance series.") OR ("improving human performance review."))*.