@article{kodama1976,
  title={A Canonical Transformation for the Sine-Gordon Equation},
  author={Yuji Kodama and Miki Wadati},
  year={1976},
  journal={Progress of Theoretical Physics},
  doi={10.1143/ptp.56.342},
  url={https://doi.org/10.1143/ptp.56.342}
}