1. Cohen, J. D. et al. Proc. natn. Acad. Sci. U.S.A. 77, 1078–1082 (1980).
2. Daniels, P. J. L., Yehaskel, A. S. & Morton, J. B. 13th Inter Conf. Antimicrobial Agents & Chemotherapy, Washington, Abstr. 137 (1973).
3. Davies, J. & Smith, D. I. A. Rev. Microbiol. 32, 469–518 (1978).
4. Davies, J. et al. in Topics in Infectious Diseases Vol. 2 (eds Drews, J. & Högenauer, G.) 101–114 (Springer, Vienna, 1977).
5. Hinnen, A., Hicks, J. B. & Fink, G. R. Proc. natn. Acad. Sci. U.S.A. 75, 1929–1933 (1978).