4Campbell John.Y. and Pierre Perron, 1991, "Pitfalls and opportunities:What macroeconomists should know about unit roots," NBER Maeroeconomies Annual, 6, 141-201.
5Campbell John.Y. Lettau M., Malkiel Burton G. and Xu Yexiao, 2003, "Have individual stocks become more volatile? An empirical exploration of idiosyncratic risk," Journal of Finance, 56(1), 1-43.
6Elton E.J., Gruber M.J, 1977, "Risk reduction and portfolio size: An analytical solution, " Journal of Business, 50(4), 415-437.
7French Kenneth, Schwert G. W. and Stambaugh R,1987, "Expected stock returns and volatility," Journal of Finwtcial Economics,19, 3-30.
8Merton, Robert C. 1980, "On estimating the expected returns on the market: An exploratory investigation," Journal of Financial Economics,8, 323-361.
9Nelson,Daniel. 1992, "Filtering and forecasting with raisspecified ARCH models: Getting the right variance with wrong models," Journal of Econometrics,S2, 61-90.
10Schwert G. W. 1989, "Why does stock market volatility change over time," Journal of Finance, 44 (5), 1115-1153.
