Perhaps you should try some spelling variations:
"improving overall performance contract." » "improving overall performance contracts.", "improving average performance contract.", "improving thermal performance contract.", "improving governance performance contract.", "improving coverage performance contract.", "improving rural performance contract.", "improving poverty performance contract."
"improving bank performance series." » "improving bank performance metrics.", "improving bank performance reviews.", "improving bank performance review.", "improving market performance series.", "improving _ performance series.", "improving firm performance series.", "improving land performance series.", "improving urban performance series.", "improving basic 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 bank performance series.") or ("improving overall performance contract."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving bank performance series.") OR ("improving overall performance contract.")).
• Removing quotes may allow a broader search: (( improving bank performance series. ) or ( improving overall performance contract. )).
• Adding a wildcard symbol may retrieve word variants: (("improving bank performance series.") or ("improving overall performance contract."))*.