Chapter Seven of The Beginnings of Rome: Italy From the Bronze Age to the Punic Wars (Circa 1,000 to 264 B.C.) by T.J. Cornell is titled The Reforms of Servius Tullius and deals with the history of the tribes, the early composition of the legions, and the comitia centuriata. This chapter again teaches pitfalls when interpreting history from ancient sources, and even Cornell himself this time is largely forced into conjecture. As so often, he makes sense, but it is probably not the last word on the subject.
Here are N.S. Gill's comments: Chapter 7 - Reforms of Servius Tullius - To Thwart the Patricians?
(This is the last chapter for Wednesday's chat.)