the prove of the effective mass of CDW

sarir_sss

i need this prove ..this formula is in many of article but they didn't point to prove.. i just find the one who proved it was frolich in the article:"On the Theory of Superconductivity: The One-Dimensional Case".. i try to found this article but i have to buy it .. is there anyone who can get it ? or even know the prove of the effective mass of cdw? ifound it obtain by mean field theory? ineed the prosses of prove.. plz help if u can.. thanks aloooooot