Chemische Berichte, , vol. 84, p. 122,123 Chemische Berichte, , vol. 77/79, p. 257,262 Chemische Berichte, , vol. 83, p. 227,234 Journal of Polymer Science, , vol. 3, p. 336,518, 646 Journal of the American Chemical Society, , vol. 78, p. 1044