I don't have a good introductory reference, to be honest. I was first exposed to it (and RG) in my 2nd year in physics grad school, and to be frank did not und

I don't have a good introductory reference, to be honest. I was first exposed to it (and RG) in my 2nd year in physics grad school, and to be frank did not understand it at all then (partly due to crap teaching).