Stressfire II: Advanced Combat Shotgun, so far I'm digging it and as an added bonus there lots of mention of the Benelli M1 121 which is what I purchased back in December so I might get to learn a few tips and tricks on my own chosen platform...of course it also means that my choice in shotguns is a little outdated, but that's OK by me for the time being.
There weren't that many books, on "tactical" shotgunning, I also ordered the Suarez book, The Tactical Shotgun: The Best Techniques And Tactics For Employing The Shotgun In Personal Combat.
Up until know most of what I know about "tactical" shotgunning has been read on gun forums....IE half to three-quarters is crap so when I decided that I wanted to delve deeper into it before heading out for an actual honest to goodness shotgun course I decided to hit the books.
Anyone can spout off BS on the internet, it takes a lot more clout to get an actual book published. Don't fear dead tree media.