Amy Gale Rodney G. Downey On Genericity and Ershov's Hierarchy. 161-182 2001 47 Math. Log. Q. 2 http://dx.doi.org/10.1002/1521-3870(200105)47:2<161::AID-MALQ161>3.0.CO;2-E db/journals/mlq/mlq47.html#GaleD01