1. China Internet Network Information Center,
http://www.cnnic.net.cn/
2. Google,
http://en.wikipedia.org/wiki/Goolge
3. Facebook,
http://baike.soso.com/v214498.htm
4. yahoo,
http://en.wikipedia.org/wiki/Yahoo
5. Chang, F., Dean, J., Ghemawat, S.: Bigtable: A distributed storage system for structured data. J. ACM Transactions on Computer Systems (TOCS) 26(2), 4 (2008)