Temperature dependence of the upper critical field of type-II   superconductors from isothermal magnetization data. Application to high   temperature superconductors
  Using the Ginzburg-Landau theory in very general terms, we develop a simple scaling procedure which allows to establish the temperature dependence of the upper critical field and the value of the superconducting critical temperature Tc of type-II superconductors from measurements of the reversible isothermal magnetization. An analysis of existing experimental data shows that the normalized dependencies the upper critical field on T/Tc are practically identical for all families of high temperature superconductors at all temperatures for which the magnetization data are available. 
I. L. Landau and H. R. Ott