1. Recursive labelling systems and stability of recursive structures in hyperarithmetical degrees;Ash;Trans. Am. Math. Soc.,1986
2. C.J. Ash, P. Cholak, J.F. Knight, Permitting, forcing, and copies of a given recursive relation, Ann. Pure Appl. Logic, to appear.
3. C.J. Ash, J.F. Knight, J.B. Remmel, Quasi-simple relations in copies of a given recursive structure, Ann. Pure Appl. Logic, to appear.
4. Recursive structures and Ershov's hierarchy;Ash,1995
5. Intrinsically recursive relations;Ash,1981