Industrial and Engineering Chemistry, , vol. 19, p. 1010 Chem. Zentralbl., , vol. 98, # II p. 2748 Helvetica Chimica Acta, , vol. 6, p. 1139 Industrial and Engineering Chemistry, , vol. 19, p. 418 Chem. Zentralbl., , vol. 98, # II p. 1831