Dear all: Now I am trying hard to interpret superconductivity in MgB2, and when reading some paper such as J.Kortus et. al, J.M.An et. al on PRL/PRB, I find that their way to weigh transition temperature is different, for instance, in J.Kortus's paper(PRL86,4656(2001)), they use McMillan-Hopfield formulate, while in J.M.An's paer(PRL86, 4366(2001)), they use Allen-Dynes's equation( relatet to "deformation potential due to frozen-in phonon?), and some other papers use Eliasberg theory, here I am a little confused: 1 which is more precise? 2 is there any difference between them?(certainly, but plz outline the differences on a more general aspects, for example, strong electron-phonon coupling, etc) 3 plz refer me to one or two classic book which would include all or part of these theories. Thank you all.