1. Anderson, E. S. Nature 208, 1016–1017 (1965).
2. Jacob, A. E. et al. in DNA Insertion Elements, Plasmids and Episomes (eds Bukhari, A. I., Shapiro, J. A. & Adhya, S. L.) 607–638 (Cold Spring Harbor Laboratory, New York, 1977).
3. Willetts, N. & Crowther, C. Genet. Res. 37, 311–316 (1981).
4. Bradley, D. E. Plasmid 4, 155–169 (1980).
5. Datta, N., Hughes, V. & Nugent, M. in Plasmids of Medical, Environmental and Commercial Importance (eds Timmis, K. N. & Pühler, A.) 175–182 (Elsevier, Amsterdam, 1979).