Perhaps you should try some spelling variations:
"improving larval performance contract." » "improving larval performance contracts.", "improving level performance contract.", "improving thermal performance contract.", "improving maximal performance contract.", "improving local performance contract.", "improving legal performance contract.", "improving land performance contract."
"improving farmers performance series." » "improving firms performance series.", "improving markets performance series.", "improving workers performance series.", "improving farmers performance studies.", "improving farmers performance size.", "improving access performance series.", "improving care 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 larval performance contract.") or ("improving farmers performance series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving larval performance contract.") OR ("improving farmers performance series."))*.
• Removing quotes may allow a broader search: (( improving larval performance contract. ) or ( improving farmers performance series. ))*.