Hoppe-Seyler's Zeitschrift fuer Physiologische Chemie, , vol. 175, p. 237,238 Journal of the American Chemical Society, , vol. 44, p. 1585 Journal of the American Chemical Society, , vol. 70, p. 1975 Biochemische Zeitschrift, , vol. 312, p. 349 Biochemische Zeitschrift, , vol. 313, p. 266