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 firms performance evidence." » "improving firm performance evidence.", "improving firm performances evidence.", "improving funds performance evidence.", "improving farmers performance evidence.", "importing firms performance evidence.", "improving air performance evidence."

Try widening your search to All Fields.

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