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2. Likelihood and the Bayes procedure;Akaike,1980
3. A nonstationary time series model and its fitting by a recursive filter;Kitagawa;Journal of Time Series Analysis,1981
4. A data analytic approach to the smoothing problem and some of its variations;Brotherton,1981
5. On the fitting of non-stationary autoregressive models in time series analysis;Ozaki,1975