1. N. J. Palleroni, “Bergey’s Manual of Systematic Bacteriology,” 1st Ed., Vol. 1, The Williams and Wilkins, Baltimore, 1984. pp. 140–219.
2. S. T. Cowan, in “Cowan and Steel’s Manual for Identification of Medical Bacteria,” 2nd Ed., Cambridge University Press, Cambridge, 1974, pp. 77–122.