1. F. V. McCann, in: Electrical Phenomena in the heart, p. 293. Ed. W. de Mello. Academic Press, New York 1972.
2. R. Hirakow and T. Gotoh, in: Developmental and Physiological Correlates of Cardiac Muscle, p. 21. Ed. M. Lieberman and T. Sano. Raven Press, New York 1976.
3. F. Manasek, in: Cell Biology: a Series of Monographs. Developmental Regulation: Aspects of Cell Differentiation, p. 193. Ed. S. Coward. Academic Press, New York 1973.
4. J. C. Jones, in: The Circulatory System of Insects, p. 5. C. C. Thomas Publications, 1977.
5. D. Fischman, in: Current Topics in Developmental Biology, vol. 5, p. 235. Ed. A. Moscona and A. Monroy. Academic Press, New York 1970.