Perhaps you should try some spelling variations:
22knowledge economy » knowlege economy, knowledge economy's
knowledge economic » knowledge economies
knowledge ecology » knowledge technology, knowledge sociology, knowledge ecologies
knolwedge economy » knowlege economy, knowledge economy's

Try widening your search to All Fields.

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: %((((((((22knowledge economy) OR (knowledge ecology))) OR (knolwedge economy))) OR (knowledge economic))) OR (knowledge economy))%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%((((((((22knowledge economy) OR (knowledge ecology))) or (knolwedge economy))) or (knowledge economic))) or (knowledge economy))%22".
• Adding a wildcard symbol may retrieve word variants: %((((((((22knowledge economy) OR (knowledge ecology))) or (knolwedge economy))) or (knowledge economic))) or (knowledge economy))%22*.