Aritonang, T.R., Rahayu, S., Sirait, L.I., Br Karo, M., Simanjuntak, T.P., Natzir, R., Sinrang, A.W., Massi, M.N., Hatta, M. and Kamelia, E. 2017. The Role of FSH, LH, Estradiol and Progesterone Hormone on Estrus Cycle of Female Rats. International Journal of Sciences: Basic and Applied Research (IJSBAR). 35, 1 (Jul. 2017), 92–100.