1. Kit, S., J. Mol. Biol., 3, 711 (1961).
2. Sueoka, N., J. Mol. Biol., 3, 31 (1961).
3. Corneo, G., Ginelli, E., Soave, C., and Bernardi, G., Biochemistry, 7, 4373 (1968).
4. Waring, M., and Britten, R. J., Science, 154, 791 (1966).
5. Walker, P. M. B., Flamm, W. G., and McLaren, A., Handbook of Molecular Cytology (edit. by Lima-de-Faria, A.), 53 (North Holland, Amsterdam, 1970).