A Decidable Ehrenfeucht Theory with Exactly Two Hyperarithmetic Models

@article{Reed1991ADE,
  title={A Decidable Ehrenfeucht Theory with Exactly Two Hyperarithmetic Models},
  author={Robert C. Reed},
  journal={Ann. Pure Appl. Logic},
  year={1991},
  volume={53},
  pages={135-168}
}