Books Online for this is actually pretty good. Its thorough and links to some other useful articles about TDE.
I know this is the 2014 forum but the SQL Server 2012 Security Best Practice Whitepaper is good and talks about TDE.
Other than that I have actually found that SSC is a great resource. Check out:
Stairway to SQL Server Security [/url] specifically, Stairway to SQL Server Security Level 9: Transparent Data Encryption[/url]
TDE and SQL Server Databases[/url] by Perry Whittle
-- Itzik Ben-Gan 2001