From what I know, there are three RC guidebooks: (1) Manhattan RC
, (2) Veritas
RC, and (3) Powerscore RC
Bible. The third book is bigger than the others, but it's actually an LSAT guide and quite expensive. Manhattan RC
generally receives lukewarm reviews. I don't know enough about the Veritas
I'm a firm believer in lots of practice for RC improvement. But if feel that an RC guidebook will help, then just purchase one of the above options. Any more than that would be a waste of money and time.