Clustered Index uses Binary Tree or Balanced tree

Hi All,

In the below mentioned link -- it says clustered index uses Binary tree

http://www.codeproject.com/Articles/173275/Clustered-and-Non-Clustered-Index-in-SQL

where as in the Querying SQL Server 2012(70-461) -- it says clustered index uses Balanced tree

Please clarify which one is correct.

Thanks,

Anilkumar