In addition to the references by Richard Hardy, the following may be helpful:

Bierens, Unit Roots, Ch. 29 in "A Companion to Theoretical Econometrics", https://onlinelibrary.wiley.com/doi/10.1002/9780470996249.ch30

A Primer for Unit Root Testing (Palgrave Texts in Econometrics) Hardcover by K. Patterson https://www.amazon.de/Primer-Testing-Palgrave-Texts-Econometrics/dp/1403902046