I can perform this bootsrap unit root test but I did not find the critical values on Smith et al (2004)'s article. How can I find the critical values in different significance level (1-5-10%).
Please consult Statistical Methods for Agricultural Workers by V.G. Panse and P. V. Sukhatme, where you will find critical values in different significant levels both values for "t" and "F" test. The book was published by Indian Council of Agricultural Research, New Delhi.