1. D. C. Langreth, in: Linear and Nonlinear Electron Transport in Solids (J. T. Devreese and E. Van Doren, Plenum, New York (1976).
2. K. C. Chou et al, Phys. Rep.
118, 1 (1985).
3. J. Rammer and H. Smith, Rev. Mod. Phys. 58, 323 (1986).
4. J. Rammer, Master’s Thesis, University of Copenhagen (1980) unpublished (in Danish).
5. L. P. Kadanoff and G. Baym, Quantum Statistical Mechanics, Benjamin, New York (1962).