- Z. Reichstein, B. Youssin, “A birational invariant for algebraic group actions”, Pacific J. Math., 204, no. 1, 2002, 223
- Andrzej Białynicki-Birula, 131, Algebraic Quotients. Torus Actions and Cohomology. The Adjoint Representation and the Adjoint Action, 2002, 1