Comments on the paper of G. Li, K. H. R. Moelle and J. A. Lewis Fatigue crack growth in brittle sandstones, Int. J. Rock Mech. Min Sci. & Geomech. Abstr. 29, 469-477 (1992) - Nóbrega, C. A. [UNESP]; Celestino, T. B. (Elsevier, 1995)