1. P. W. Anderson Basic notions of condensed matter physics (Benjamin-Cummings, 1984).
2. S. Ma, Modern theory of critical phenomena, 46 (Da Capo Press, 2000).
3. T. Senthil, International Journal of Modern Physics B 20, 2603 (2006).
4. K. v. Klitzing, G. Dorda, and M. Pepper, Phys. Rev. Lett. 45, 494 (1980).
5. D. C. Stormer, and A. C. Gossard, Phys. Rev. Lett. 48, 1559 (1982).