1. M. Buttiker, Time in Quantum Mechanics (Springer, 2001), pp. 279–303
2. C.R. Leavens, G.C. Aers, Phys. Rev. B 39, 1202 (1989)
3. S. Mukherjee et al., Physica E 44, 62 (2011)
4. J.M. Ziman, Principles of the Theory of Solids, 2nd edn. (Cambridge University Press, 1979)