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2. Karnovsky, D. A., in: Wilson, J. G., Warkany, J.: Teratology, Priciples and Techniques, S. 185. Chicago-London 1965; Tencer, R.: Exp. Cell Res.23, 418 (1961);
3. Bieliavsky, N., Leong, G. F.: ibid. Exp. Cell Res.47, 261 (1967).
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