Automorphisms of Models of True Arithmetic: Subgroups which Extend to a Maximal Subgroup Uniquely.

Bozena Piekart Henryk Kotlarski Automorphisms of Models of True Arithmetic: Subgroups which Extend to a Maximal Subgroup Uniquely. 95-102 1994 40 Math. Log. Q. db/journals/mlq/mlq40.html#PiekartK94