1. 1) V. de Vlaming, G. Grossman, and F. Chapman: On the use of the gonadosomatic index. Comp. Biochem. Physiol., 73 A, 31-39(1982).
2. 2) Y. Nagahama: Gonadotropin action on gametogenesis and steroido-genesis in teleost gonads. Zool. Sci., 4, 209-222 (1987).
3. 3) N. Stacey, J. R. Cardwell, N. R. Liley, A. P. Scott, and P. W. Sorenson: Hormones as sex pheromones in fish, in “Perspectives in Comparative Endocrinology” (ed. by K. G. Davey, R. E. Peter and S. S. Tobe), National Research Council of Canada, Ottawa, 1994, pp. 438-448.
4. 4) M. Kobayashi, K. Aida, and I. Hanyu: Involvement of steroid hormones in the preovulatory gonadotropin surge in female goldfish. Fish Physiol. Biochem., 7, 141-146 (1989).
5. 5) M. Kobayashi and N. Stacey: Effects of Ovariectomy and steroid hormone implantation on serum gonadotropin levels in female goldfish. Zool. Sci., 7, 715-721 (1990).