Perhaps you should try some spelling variations:
"improving contract performance series." » "improving country performance series.", "improving court performance series.", "improving economic performance series.", "improve contract performance series.", "improving central performance series.", "improve contrast performance series.", "improving contract performance studies.", "improving contract performance size."
"improving road performance review." » "improving road performance risk.", "improving road performance evidence.", "improving board performance review.", "improving good performance review.", "improving bond performance review.", "improving food performance review.", "improving rural 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: (("improving contract performance series.") OR ("improving road performance review."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"improving contract performance series.\") OR (\"improving road performance review.\"))".
• Removing quotes may allow a broader search: (( improving contract performance series. ) OR ( improving road performance review. )).
• Adding a wildcard symbol may retrieve word variants: (("improving contract performance series.") OR ("improving road performance review."))*.