On the theory of testing for unit roots in observed time series

1.On the theory of testing for unit roots in observed time series,Review of Economic Studies,Volume 53, Issue 3,Pp. 369-384
2.Testing for a unit root in the presence of moving average errors,Biometrika,Volume 76, Issue 1,Pp. 49-56
3.Peter C.B. Phillips,Sam Ouliaris,Testing for a Unit Root in the Presence of a Maintained Trend
4.R F Engle, C W J Granger ,Co-integration and error correction: Representation, estimation and testing (1987)  

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