Perhaps you should try some spelling variations:
"improving human performance contract." » "improving human performance contracts.", "improving loan performance contract.", "improving thermal performance contract.", "improving chain performance contract."
"improving farmers performance metrics." » "improving firms performance metrics.", "improving markets performance metrics.", "improving workers performance metrics.", "improving farmers performance measures.", "improving access performance metrics.", "improving care performance metrics."

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