@article{Hayakawa:4799,
      author        = "Hayakawa, Hisashi and Clette, Frédéric and Horaguchi,
                       Toshihiro and Iju, Tomoya and Knipp, Delores J. and Liu,
                       Huixin and Nakajima, Takashi",
      title         = "{Sunspot observations by Hisako Koyama: 1945-1996}",
      year          = "2020",
}