Helvetica Chimica Acta, , vol. 10, p. 580,583 Journal of the Chemical Society, , p. 614 Helvetica Chimica Acta, , vol. 16, p. 1343 Justus Liebigs Annalen der Chemie, , vol. 554, p. 118 Justus Liebigs Annalen der Chemie, , vol. 554, p. 118 Anm. Journal of the Chemical Society, , vol. 107, p. 1027 Journal of the Chemical Society, , vol. 123, p. 1042