Fisher, N.I. (1993) Statistical analysis of circular data. Cambridge University Press.
Shepherd, J. and Fisher, N.I. (1981) A rapid method of mapping fracture trends in collieries.
Aust. Coal Miner August, 24-33.
Shepherd, J. and Fisher, N.I. (1982) A rapid method of mapping fracture trends in collieries.
Trans. Soc. Min. Eng. AIME 270, 1931-2.