Popov V.L., “On the Makar-Limanov, Derksen Invariants, and Finite Automorphism Groups of Algebraic Varieties”, Affine Algebraic Geometry: the Russell Festschrift, CRM Proceedings & Lecture Notes, 54, ed. Daigle D. Ganong R. Koras M., Amer Mathematical Soc, 2011, 289–311