1. http://www.cio.com/article/32050/2004_The_Year_of_Web_Services
2. http://oreilly.com/web2/archive/what-is-web-20.html
3. Participative Web: User-Created Content: Web 2.0, Wikis and Social Networking;Wunsch-Vincent,2007
4. Volunteered geographic information: The nature and motivation of producers;Coleman;Int. J. Spat. Data Infrastruc. Res.,2009
5. Citizens as sensors: the world of volunteered geography