To appear in Journal of Logic, Language and Information.

Journal of Logic, Language and Information 3/2 (1994): 141-168.

Journal of Logic and Computation 15(4) (2005), pages 447-463.

Journal of Logic and Computation 15(2), pages 201-218, 2005.

Journal of Logic and Computation Volume 20, Issue 2, 2010, pages 573-595.

Journal of Logic and Computation 16 (2006), pages 489-532.

Journal of Symbolic Logic 72 (2007), pages 243-276.

From 1960 to his death he was an editor of the Journal of Symbolic Logic.

Journal of Logic and Computation 8, 809-838, 1998.

Journal of Symbolic Logic v. 50 n. 2, pp.