[Big V]

I have been playin NL for about a year, mainly in online tournaments. I did read super system but I felt about the same as most people from this thread did (its got some good points, but not a perfect strategy anymore). My friends are now getting started playing, and I would like to recommend a good NL book for them to read as a good start, and in addition, a good book to further my own knowledge and strategy (specifically NL tournaments). Any suggestions?