Perhaps you should try some spelling variations:
"clean development studies." » "clean development services.", "clean development strategies.", "clean development strategy.", "human development studies.", "urban development studies.", "child development studies."
"_ development studies." » "_ development services.", "_ development strategies.", "_ development strategy."
"clean development series." » "clean development services.", "clean development agencies.", "clean development africa.", "human development series.", "urban development series.", "child development series."

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: (((("clean development studies.") OR ("clean development series."))) or ("_ development studies."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("clean development studies.") OR ("clean development series."))) OR ("_ development studies.")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"clean development studies.\") OR (\"clean development series.\"))) or (\"_ development studies.\"))".
• Removing quotes may allow a broader search: (((( clean development studies. ) OR ( clean development series. ))) or ( _ development studies. )).
• Adding a wildcard symbol may retrieve word variants: (((("clean development studies.") OR ("clean development series."))) or ("_ development studies."))*.