@article{CTT100857581,
  author = {Teruaki Suyama and Hayato Motohashi},
  title = {Quantum Ostrogradsky theorem},
  journal = {Journal of High Energy Physics},
  year = 2020,
}

@article{CTT100808588,
  author = {Hayato Motohashi and Teruaki Suyama and Masahide Yamaguchi},
  title = {Ghost-free theories with arbitrary higher-order time derivatives},
  journal = {Journal of High Energy Physics},
  year = 2018,
}

@article{CTT100808587,
  author = {Hayato Motohashi and Teruaki Suyama and Masahide Yamaguchi},
  title = {Ghost-free theory with third-order time derivatives},
  journal = {Journal of the Physical Society of Japan},
  year = 2018,
}