Perhaps you should try some spelling variations:
"improving city performance contract." » "improving city performance contracts.", "improving key performance contract.", "improving country performance contract.", "improving utility performance contract.", "improving eitc performance contract.", "improving equity performance contract.", "improving birth performance contract."
"improving export performance series." » "improving export performance studies.", "improving export performance size.", "improving exposure performance series.", "improving eap performance series.", "improving eco 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 export performance series.") or ("improving city performance contract."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving export performance series.") OR ("improving city performance contract.")).
• Removing quotes may allow a broader search: (( improving export performance series. ) or ( improving city performance contract. )).
• Adding a wildcard symbol may retrieve word variants: (("improving export performance series.") or ("improving city performance contract."))*.