Angewandte Chemie, , vol. 46, p. 251,252 Kunstst., , vol. 27, p. 287,288 Journal of the Society of Chemical Industry, London, , vol. 58, p. 131,138 Transactions of the Faraday Society, , vol. 32, p. 336,342 Journal of the Society of Chemical Industry, London, , vol. 49, p. 245 T, 248 T