1. Fixpoint alteration and the game quantifier;Bradfield,1999
2. Christoph Heinatsch, Zur Determiniertheitsstärke von Π21-Komprehension. Diplomarbeit, Münster, 2003.
3. Classical Descriptive Set Theory;Kechris,1995
4. D.A. Martin, Proving determinacy (forthcoming).
5. Michael Möllerfeld, Generalized Inductive Definitions. The μ-calculus and Π21-comprehension. Dissertation, Münster, 2002.