1. V. W. Rodwell, “Metabolic Pathway,” ed. by D. M, Greenberg, Academic Press, New York and London, 1969, p. 203.
2. Y. Okada, “Koden Hishokuho,” Vol. 1, ed. by T. Sekine, Y. Sasagawa, S. Morita, T. Kimura and K. Kuratomi, Nankodo, 1959, p. 65.
3. T. Suzuki and Y. Hayashi, “Aminosan series,” Vol. 6, ed. by S, Akabori, J. Ashida, K. Ichihara, T. Suzuki and M. Suda, Nankodo, 1965, p. 23.