Perhaps you should try some spelling variations:
"improving model performance contract." » "improving model performance contracts.", "improving social performance contract.", "improving pupil performance contract.", "improvement model performance contract.", "improving budget performance contract.", "improving gender performance contract."
"improving loan performance series." » "improving loan performance studies.", "improving loan performance size.", "improving local performance series.", "improving land performance series.", "improving lead 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 loan performance series.") or ("improving model performance contract."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving loan performance series.") OR ("improving model performance contract.")).
• Removing quotes may allow a broader search: (( improving loan performance series. ) or ( improving model performance contract. )).
• Adding a wildcard symbol may retrieve word variants: (("improving loan performance series.") or ("improving model performance contract."))*.