1. Akdi, Y., 1995. Periodogram analysis for unit roots. Ph.D. Dissertation, Department of Statistics, North Carolina State University, Raleigh, North Carolina.
2. Periodograms of unit root time series: distributions and tests;Akdi;Comm. Statist: Theory, Methods,1997
3. Asymptotic distribution of periodogram ordinate for a nearly nonstationary AR(1) process;Bhattacharyya;Sankhya Ser. B,1996
4. Testing for unit roots in a nearly nonstationary spatial autoregressive process;Bhattacharyya;Inst. Statist. Math.,2000
5. Time Series: Theory and Methods;Brockwell,1991