In which assembly I find namespace 'NHibernate.Proxy.Poco.Castle'?

In which assembly I find namespace 'NHibernate.Proxy.Poco.Castle'? I can find in NHibernate.dll the Pro开发者_JAVA百科xy.Poco, but not Proxy.Poco.Castle... (using Nhibernate 2.1.2.4000).

I believe that's quite old; in recent versions the namespace is NHibernate.ByteCode.Castle, and it's in NHibernate.ByteCode.Castle.dll