A characterization of determinacy for Turing degree games E. Kleinberg (1973) Fundamenta Mathematicae
A decidable ℵ 0 -categorical theory with a non-recursive Ryll-Nardzewski function James Schmerl (1978) Fundamenta Mathematicae
A note on initial segments below O̰ ' Antonín Kučera (1989) Commentationes Mathematicae Universitatis Carolinae