Key points are not available for this paper at this time.
Timothy J. Vogelsang, Pierre Perron, Additional Tests for a Unit Root Allowing for a Break in the Trend Function at an Unknown Time, International Economic Review, Vol. 39, No. 4, Symposium on Forecasting and Empirical Methods in Macroeconomics and Finance (Nov., 1998), pp. 1073-1100
Vogelsang et al. (Sun,) studied this question.