Perhaps you should try some spelling variations:
"improving overall performance contract." » "improving overall performance contracts.", "improving average performance contract.", "improving thermal performance contract.", "improving governance performance contract.", "improving coverage performance contract.", "improving rural performance contract.", "improving federal performance contract."
"improving air performance metrics." » "improving air performance measures.", "improving zur performance metrics.", "improving bar performance metrics.", "improving der performance metrics.", "improving _ performance metrics."

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 air performance metrics.") or ("improving overall performance contract."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving air performance metrics.") OR ("improving overall performance contract.")).
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• Adding a wildcard symbol may retrieve word variants: (("improving air performance metrics.") or ("improving overall performance contract."))*.