Perhaps you should try some spelling variations:
"improving birth performance based." » "improving birth performance measures.", "improving firm performance based.", "improving high performance based.", "improving port performance based.", "improving air performance based.", "improving health performance based.", "improving growth performance based."
"improving asset performance evidence." » "improving market performance evidence.", "improving based performance evidence.", "improving past performance evidence.", "improving sme performance evidence.", "improving adult 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 birth performance based.") or ("improving asset performance evidence."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving birth performance based.") OR ("improving asset performance evidence.")).
• Removing quotes may allow a broader search: (( improving birth performance based. ) or ( improving asset performance evidence. )).
• Adding a wildcard symbol may retrieve word variants: (("improving birth performance based.") or ("improving asset performance evidence."))*.