Surprising coincidence of the apparent 2D metal-to-insulator transition   data with Fermi-gas based model results
  The melting condition for two-dimensional Wigner solid ( P.M. Platzman, H.Fukuyama, 1974) is shown to contain an error of a factor of $\pi$. The analysis of experimental data for apparent 2D metal-to-insulator transition shows that the Wigner solidification (B.Tanatar, D.M.Ceperley, 1989) has been never achieved. Within routine Fermi gas model both the metallic and insulating behavior of different 2D system for actual range of carrier densities and temperatures is explained. 
M.V. Cheremisin
cond-mat.str-el