# How to fit Werthamer-Helfand-Hohenberg (WHH) equation in a Hc2 vs T equation?

The Werthamer-Helfand-Hohenberg (WHH) formula $$μ_0H_{c2}(0)=0.693μ_0T_c\frac{dH_{c2}}{dT}|T→Tc$$ was used to estimate μ$$_0$$H$$_c$$2(0) at 0 K where only orbital breaking effects are considered in the dirty limit. In various research articles this equation has been fitted with experimental $$H_{c2}$$ vs T. How can this equation be fitted? My understanding is $$\frac{dH_{c2}}{dT}|T→Tc$$ is a number, so instead of getting many numbers [which is required to fit this equation] i will get only one number. Kindly help me in this.