Use established formula for Henry coefficient Air & Water

For the temperature-dependent Henry coefficient of air in water, we use a formula from Stefan Finsterle's PhD disserttaion (1993, page 33 Formula (2.9)) derived from fitting to data from Tchobanoglous & Schroeder, 1985. See dumux/material/binarycoefficients/h2o_air.hh.

I have three issues with the formula

1. Stefan is not an expert for Henry coefficient nor are his advisors. Using such a formula from a PhD thesis is not optimal.
2. The formula and the underlying data is not easily accessible. The PhD thesis is in Swiss German and the data is from a book. It can be obtained, but online published formula would be much better.
3. The limits of the formula are currently unknown and not documented. In what temperature range are the values reliable? E.g., extrapolation data from between 15°C and 40°C from soil science to some hot PEM fuel cell case with > 100°C is probably not good.

Unfortunately, I was not able to find a better formula. Henry coefficients are published (without temperature dependency) only for pure gases like O2 or CO2, not for mixtures like air.