Perhaps you should try some spelling variations:
"clean development policies." » "clean development policy.", "clean development projects.", "human development policies.", "urban development policies."
"a development studies." » "a development series.", "a development services.", "a development strategies."
"a development process." » "a development projects.", "a development programs."

Try widening your search to All Fields.

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• Performing a fuzzy search may retrieve terms with similar spellings: (("a development studies.") or ((("a development process.") or ("clean development policies."))))~.
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• Adding a wildcard symbol may retrieve word variants: (("a development studies.") or ((("a development process.") or ("clean development policies."))))*.