[texhax] book to buy?

[mr at xosoftware.dk]

> I fear lots of people may tell you this !
> 
> The essential reading is
> 
> Lamport, Leslie
> LaTeX, A Document Preparation System
> Addison-Wesley, 1994

I borrowed it from a friend and checked it out. It seems good but not a whole
lot of pages. I would like to know more about how Latex works, that is, "the
inner workings" so to speak.I have been told that Kopka's book is very
extensive. But I don't know if it has more on "designing yourself"?!
Thanks
Martin