Roll-o-Tape aka Wykoff is good but dated. Dated in that it was based on how people traded back then. But understand what the "take with a grain of salt" comment really means. IMO it means taking the concepts and recasting them into how people trade today. People ate food back then, and still do today, but it is a very different "food world" so adjust accordingly to get any value out of 100 year old methods...