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 can performance reviews." » "improving can performance review.", "improving can performance reports.", "improving can performance risks.", "improving chain performance reviews.", "improving loan performance reviews.", "improving 2 performance reviews.", "improving care performance reviews.", "improving a performance reviews.", "improving co 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 can performance reviews."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"improving human performance studies.\") OR (\"improving can performance reviews.\"))".
• Removing quotes may allow a broader search: (( improving human performance studies. ) OR ( improving can performance reviews. )).
• Adding a wildcard symbol may retrieve word variants: (("improving human performance studies.") OR ("improving can performance reviews."))*.