1. Atkins, J.B., and Marks, J. (1952) Brit. J. industr. Med. 9, 296.
2. Barber, M., and Warren, S. (1962) Lancet, 2, 374.
3. Cowan, S.T., and Steele, K.J., (1965) “Manual for the Identification of Medical Bacteria” Cambridge University Press.
4. Davidson, A.I.G., Clark, C., and Smith, G. (1971) Brit. J. Surg. 58, 333.
5. Ericsson, H.M., and Sherris, J.C. (1971) Acta path. microbiol scand. Section B. Suppl. 217.