I have been going through a thermal physics book by Schroeder. In chapter 8 (Systems of Interacting Particles) he introduces the configuration integral in terms of pictorial diagrams describing sets of interacting particles in a weakly interacting gas. Each configuration has an associated symmetry factor, however, it is not clear how these factors are supposed to be determined. Likely the system he analyses is the canonical ensemble partition function. Is there any book that explains in more detail how these factors are calculated?