Glassfish: sources

Where are all those sources of the glassfish that one can use for addapting the behavior/studing the way it operates?

I've found following link for svn access:

https://svn.java.net/svn/glassfish~svn

Therefor as in my case if I need 3.1.1 version I can obtain it simply via:

svn co https://svn.java.net/svn/glassfish~svn/tags/3.1.1/ glassfish_3.1.1