More info on low-energy hadronic cross sections

The physics reference manual states that for low energy (< 91 GeV) hadronic cross sections, the “Barashenkov interpolations” are used (page 249). Not much info is given in the references about what these calculations are. As a counter example, the Glauber-Gribov model/parameterization (the high energy cross section) is shown and described quite clearly.

Is there any further documentation on what was used to get the low energy hadronic cross sections, for example, the values used in the G4PiNuclearCrossSection class?