Hofmann et al. Journal of the American Chemical Society, 1956 , vol. 78, p. 238,240 Full Text Show Details van Orden; Smith Journal of Biological Chemistry, 1954 , vol. 208, p. 751,753 Full Text Show Details Izumiya; Makisumi Nippon Kagaku Zasshi, 1957 , vol. 78, p. 1768,1772 Chem.Abstr., 1960 , p. 1341