git links

http://longair.net/blog/2010/06/02/git-submodules-explained/
http://chrisjean.com/2009/04/20/git-submodules-adding-using-removing-and-updating/
http://tareq.wedevs.com/2012/04/deploying-php-apps-with-git-and-git-submodule/
http://365git.tumblr.com/post/12581972612/set-up-a-submodule-where-only-you-have-write-access