Perhaps you should try some spelling variations:
development development » development developing, development environment
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 (leed) ((working papers) OR (working paper)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((oecd regional) or (chad regional)) economic and development development (leed) ((working papers) OR (working paper))".
• Adding a wildcard symbol may retrieve word variants: ((oecd regional) or (chad regional)) economic and development development (leed) ((working papers) OR (working paper))*.