1. Universality became well established after the development of renormalization group theory by K. Wilson. A good reference is J. Cardy, Scaling and Renormalization in Statistical Physics, (Cambridge University Press, Cambridge, 1996).
2. Spin Glasses and Random Fields, A. P. Young Ed., (World Scientific, Singapore, 1998)
3. K. Binder and A. P. Young, Spin Glasses: Experimental Facts, Theoretical Concepts and Open Questions, Rev. Mod. Phys. 58, 801 (1986).
4. A good review of the application of optimization methods to problems in statistical physics is H. Rieger, Frustrated Systems: Ground State Properties via Combinatorial Optimization, in Advances in Computer Simulations, Lecture Notes in Physics, 501, J. Kertész and I. Kondor Eds., (Springer-Verlag, Heidelberg, 1998). This is also available on the cond-mat archive as cond-mat/9705010. The URL for condmat is http://xxx.lanl.gov/archive/cond-mat .
5. According to statistical mechanics, a system in thermal equilibrium has a probability proportional to exp(-El/kBT) of being in a state l with energy El, where T is the temperature, and kB is Boltzmann’s constant (usually set to unity in model calculations). This exponential is known as a “Boltzmann factor”.