The Index Set of Injectively Enumerable Classes of Recursively Enumerable Sets is Sigma<sub>5</sub>-Complete.

Stephan Wehner The Index Set of Injectively Enumerable Classes of Recursively Enumerable Sets is Sigma<sub>5</sub>-Complete. 87-94 1994 40 Math. Log. Q. db/journals/mlq/mlq40.html#Wehner94