Perhaps you should try some spelling variations:
"improving thermal performance contract." » "improving thermal performance contracts.", "improving external performance contract.", "improving animal performance contract.", "improving erm performance contract."
"improve lanterns performance evidence." » "improve blaster performance evidence.", "improve center performance evidence.", "improve clusters performance evidence.", "improve matern performance evidence.", "improve water performance evidence.", "improve maternal performance evidence."

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 ("improve lanterns performance evidence."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving thermal performance contract.") OR ("improve lanterns performance evidence."))*.
• Removing quotes may allow a broader search: (( improving thermal performance contract. ) or ( improve lanterns performance evidence. ))*.