GLSL Info?

Hello fellow developers, I''m giving my first steps in shader programing and need some help finding my way. I''m looking for an introductory document concerning the OpenGL Shading Language, something similar to the "Blue book". Not tutorials, but a real document. Something like the document that comes with the Cg package, wich describes the language, gives some introductory firs steps and then some examples. Complete and nice. I found the spec at Opengl.org (http://www.opengl.org/documentation/oglsl/ShaderSpecV1.051.pdf) but even though it''s a nice reading it is simply limiting itself to describing the language (well, that''s why it''s a spec, i guess). So, anyone knows if this type of doc i''m looking for exists? Thanks and sorry if this has been asked frequently.