Perhaps you should try some spelling variations:
development development » development environment
working papers » working paper
oecd regional » oecd regions, world regional
chad regional » chad region

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: ((oecd regional) OR (chad regional)) economic AND ((development development) OR (development developing)) (leed) working papers.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((oecd regional) or (chad regional)) economic and ((development development) OR (development developing)) (leed) working papers".
• Adding a wildcard symbol may retrieve word variants: ((oecd regional) or (chad regional)) economic and ((development development) OR (development developing)) (leed) working papers*.