7Engle R F. Autoregressive conditional heteroscedasticity with estimates of the variance of united kingdom inflation [J]. Econometrica, 1982,50 (4): 987~1007.
8Bollerslev T. Generalized autoregressive conditional heteroscedasticity [J]. Journal of Econometrics, 1986,31:307~327.
9Nelson D B. Conditional heteroscedasticity in asset returns: a new appoach [J]. Econometrica, 1991,59 (2):347~370.