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

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 (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 (knolwedge economy))) or (knowledge economic))) or (knowledge economy))%22".
• Adding a wildcard symbol may retrieve word variants: %((((((22knowledge economy) OR (knolwedge economy))) or (knowledge economic))) or (knowledge economy))%22*.