Perhaps you should try some spelling variations:
"improving job performance contract." » "improving job performance contracts.", "improving court performance contract.", "improving co performance contract.", "improving food performance contract.", "improving crop performance contract."
"improving rural performance series." » "improving rural performance studies.", "improving rural performance size.", "improving euract performance series.", "improving larval performance series.", "improving pupil performance series."

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

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