Perhaps you should try some spelling variations:
"improving thermal performance series." » "improving thermal performance studies.", "improving thermal performance size.", "improving external performance series.", "improving animal performance series.", "improving erm performance series."
"improving thermal performance reports." » "improving external performance reports.", "improving animal performance reports.", "improving erm performance reports.", "improving thermal performance report."

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