Perhaps you should try some spelling variations:
"improving thermal performance contract." » "improving thermal performance contracts.", "improving maternal performance contract.", "improving human performance contract.", "improving mental performance contract."
"improving rural performance measures." » "improving pupil performance measures.", "improving overall performance measures.", "improving fiscal performance measures.", "improving urban performance measures.", "improving social performance measures."

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 thermal performance contract.") or ("improving rural performance measures."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving thermal performance contract.") OR ("improving rural performance measures.")).
• Removing quotes may allow a broader search: (( improving thermal performance contract. ) or ( improving rural performance measures. )).
• Adding a wildcard symbol may retrieve word variants: (("improving thermal performance contract.") or ("improving rural performance measures."))*.