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

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