Perhaps you should try some spelling variations:
"improving firms performance review." » "improving firms performance risk.", "improving firms performance evidence.", "improving firm performance review.", "improving firm performances review.", "improving funds performance review.", "improving farmers performance review.", "importing firms performance review.", "improving air performance review."
"improving road performance series." » "improving road performance studies.", "improving road performance size.", "improving board performance series.", "improving good performance series.", "improving bond performance series.", "improving food performance series.", "improving rural performance series."

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("improving firms performance review.") or ("improving road performance series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving firms performance review.") OR ("improving road performance series.")).
• Removing quotes may allow a broader search: (( improving firms performance review. ) or ( improving road performance series. )).
• Adding a wildcard symbol may retrieve word variants: (("improving firms performance review.") or ("improving road performance series."))*.