Methods for storage of Gibbs energy data of substances

There are two popular methods for storing Gibbs energy data for pure substances. They are inspired by Planck and by Lewis and Randall and may appear as very different but it will be demonstrated that they only differ by the choice of references. The derivation of functions to be stored will then be described and a crude but very simple method for extending them to 0 K by interpolation instead of extrapolation will be presented.