Hi everybody. I was given a project to calculate Callan-Symanzik beta function of QED and QCD (with massless fermions) to one loop order. This problem is actually solved in Peskin, BUT without the needed rigor, plus with funny assumptions and also a few mistakes. I have tried for a long time to find where this topic is covered in the manner it is covered in Peskin, but it seems that Peskin's access to the problem although not quite clear to me is pretty original. (Even Callan's original article is not sharing the same access) My question is: Does anyone knows where I can find literature dealing with Renormalization group from Callan-Symanzik's point og view, and most simillar to Peskin's access to that issue ? Thanks ahead.