Perhaps you should try some spelling variations:
"Improving company performance contract." » "Improving company performance contracts.", "Improving country performance contract.", "Improving loan performance contract.", "Improving corporate performance contract."
"improving human performance series." » "improving human performance metrics.", "improving human performance reviews.", "improving human performance review.", "improving loan performance series.", "improving thermal performance series.", "improving animal performance series.", "improving urban performance series.", "improving rural performance series."

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