. Notation systems for infinitary derivations. Archive for mathematical logic, vol. 30 no. 5–6 (1991), pp. 277–296.
. Explaining Gentzen's consistency proof within infinitary proof theory. Computational logic and proof theory, 5th Kurt Gödel colloquium, KGC '97, Vienna, Austria, August 25–29, 1997, Proceedings, edited by
, Lecture notes in computer science, vol. 1289, Springer, Berlin, Heidelberg, New York, etc., 1997, pp. 4–17.
. Finitary reductions for local predicativity, I: recursively regular ordinals. Logic Colloquium '98, Proceedings of the annual European summer meeting of the Association for Symbolic Logic, held in Prague, Czech Republic, August 9–15, 1998, edited by
, Lecture notes in logic, no. 13, Association for Symbolic Logic, Urbana, and A K Peters, Natick, Mass., etc., 2000, pp. 465–499.