Content problem - content that used to be there is gone - where did it go?

I've looked through all the links on the Documentation page but can't find some content that I used to reference a lot. This was very a specific "mini-book" with multiple chapters about nodes, blocks, users, etc - and there were exercises, including sample emails from your Boss saying let's do this now, let's add this person, let's make this specific change...one person who left a comment on it said if they had read this before they starting doing anything else with Drupal they would have advanced so much faster. As I recall, this link didn't really seem to belong on the page where it was located (I remember specifically it used to be just one page off the Drupal.org home page and the link was over on the right side) but I kept going back to it over and over since it was such a great reference. Here's hoping someone who reads this has a clue what I'm talking about and will recall seeing where it has been moved to (I sure hope it hasn't been totally deleted...if so, someone went to an awful lot of work for no reason!)