1. D. A. Roland, in “Food, Nutrition and Diet Therapy,” 6th Ed., ed. by M. V. Krause and L. K. Mahan, W. B. Saunders Company, Philadelphia–London–Toronto, 1979, pp. 777–804.
2. Y. Hojo and J. Ishizuka, “Experimental Methods of Plant Physiology” (in Japanese), Nogyo Gijutsu Kyokai, Tokyo, 1985, pp. 281–283.
3. K. Shibata, “Basic Statistics for Biologists” (in Japanese), Sobun, Tokyo, 1974, pp. 64–78.