1. Wolff, E. in Regeneration (ed. Rudnick, D.) 53–84 (Ronald Press Co., New York, 1962).
2. Hay, E.D. in The Stability of the Differentiated State (Springer-Verlag, Berlin/Heidelberg, 1978).
3. Gregmigni, V. & Puccinelli, I. J. Exp. Zool. 199, 57 (1977).
4. Gregmigni, V., Miceli, C. & Puccinelli, I. J. Embryol. Exp. Morph. 55, 53 (1980).
5. Gregmigni, V., Miceli, C. & Picano, E. J. Embryol. Exp. Morph. 55, 65 (1980).