1. T. Gibson and R. E. Gordon, “Bergey’s Manual of Determinative Bacteriology,” 8th Ed., ed. by R. E. Buchanan and N. E. Gibbons, The Williams & Wilkins Company, Baltimore, 1975, p. 529.
2. P. H. A. Sneath, “Bergey’s Manual of Systematic Bacteriology,” Vol. 2, ed. by P. H. A. Sneath, N. S. Mair, M. E. Sharpe and J. G. Holt, The Williams & Wilkins Company, Baltimore, 1986, p. 1105.