1. The statistical analysis of time series;Anderson,1971
2. A new test for heteroscedasticity;Glejser;Journal of the American Statistical Association,1969
3. Nonlinear methods in econometrics, Ch. 3:Analyses of heteroscedasticity;Goldfeld,1972
4. Some estimators for a linear model with random coefficients;Hildreth;Journal of the American Statistical Association,1968