1. D. P. Kelly, in “The Nitrogen and Sulfur Cycles,” ed. by J. A. Cole and S. J. Ferguson, Cambridge University Press, Cambridge, 1988, pp. 65–98.
2. J. G. Kuenen, J. T. Pronk, W. Hazeu, R. Meulenberg, and P. Bos., in “Biohydrometallurgical Technologies,” Vol. II, ed. by A. E. Torma, M. L. Apel. and C. L. Brierley, TMS Society, Pennsylvania, 1993, pp. 487–494.