Perhaps you should try some spelling variations:
"improving human performance studies." » "improving human performance audits.", "improving human performance audit.", "improving human performance standards.", "improving loan performance studies.", "improving thermal performance studies.", "improving chain performance studies."
"improving care performance reviews." » "improving care performance review.", "improving care performance reports.", "improving care performance risks.", "improving trade performance reviews.", "improving drive performance reviews.", "improving 2 performance reviews.", "improving early performance reviews.", "improving air performance reviews.", "improving data performance reviews."

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("improving human performance studies.") or ("improving care performance reviews."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving human performance studies.") OR ("improving care performance reviews.")).
• Removing quotes may allow a broader search: (( improving human performance studies. ) or ( improving care performance reviews. )).
• Adding a wildcard symbol may retrieve word variants: (("improving human performance studies.") or ("improving care performance reviews."))*.