Experimental data (scattered lines) and corresponding fitting results (solid lines). Three major types of high T_c cuprate superconductors are represented: (a) Tl-1223, (b) optimally doped Y-123, (c) Bi-2212. Each set of curves uses just three fitting parameters, H_c2, γ, and κ. The experimental data can be found in Refs. [18], [32], and [33].