1Judge G, W Griffiths, R Hill, H Lutkepohl and T Lee, 1985, The Theory and Practice of Econometrics. New York. John Wiley and Soils.
2Levin A, C F Lin and C S Chu, 2002, Unit root tests in panel data. Asymptotic and finite sample properties. Journal of Econometrics 108, 1-24.
3Nefici S N. 1985, A note on the use of local maxima to predict turning points in related series. Journal of the American Statistical Association 80, 553-557.
4Bar-Hen A and J J Daudin, 1995, Generalization of the Mahalanobis distance in the mixed case, Journal of Multivariate Analysis 53,332-342.
5Bedrick E J , J Lapidus and J F Powell, J F. 2000, Estimating the Mahalanobis distance from mixed continuous and discrete data,Biometrika 56, 394-401.
6Chu C J and H White, 1992, A direct test for changing trend, Journal of Business and Economics Statistics 10, 289-299.
7Ira K, M Pesaran and Y Shin, 1997. Testing for unit roots in heterogeneous panels. University of Cambridge Working Paper.