Ratio h(v) (Eq. (B.10)) of the second-order integrated Taylor-expansion to the zeroth order for the two H-p charge exchange cross-sections discussed by Fite et al. (1962) and Lindsay & Stebbings (2005). The bump between the two downward spikes in the Lindsay-Stebbings curve is negative, but to represent it in a logarithmic scale, its absolute value was taken. See text for restrictions of the fit functions.