Very very few. Reading the back of surgical recall should suffice. The only thing extra I did was looking through the "trauma" section of different subspecialties in BRS. For me Recall and BRS did the job nicely.
I disagree. I found that Recall was great before cases and the couple of days right before the shelf. I wouldn't use it as my primary recource though. Pretest was also good. BRS was more useful for learning concepts and facts at length (I hate Lawrence).
The ABSITE review is also a great book. It is very very concise, but it is up to date, and has most of the important stuff you need to know for the exam. This is the only book I used to study for the sub-specialties. It's a small book, so you can keep it in your white coat. I used that, the appleton and lange question book, and the BRS, and got in the 95th percentile.