The JGR paper on effective stress is rather long and complicated. A summary of the main results is given in tabular form in the following paper:

J. G. Berryman, `` Effective-stress rules for pore-fluid transport in rocks containing two minerals,'' Int. J. Rock Mech. Min. Sci. & Geomech. Abst. 30, 1165-1168 (1993).