1. Association of Official Analytical Chemists, “Official Methods of Analysis of the A.O.A.C,” 12th Ed., A.O.A.C., Washington, D.C., 1975, pp. 129 ~ 146.
2. M. E. Coates, “Clinical and Experimental Gnotobiotics (Zbl. Bakt. Suppl. 7)”, ed. by T. Fliedner, H. Heit, D. Neithammer and H. Pflieger, Gustav Fischer Verlag, Stuttgart and New York, N.Y., 1979, pp. 29 ~ 37.