To cite iNEXT.4steps in publications use:

Chao, A., Y. Kubota, D. Zelený, C.-H. Chiu, C.-F. Li, B. Kusumoto, M. Yasuhara, S. Thorn, C.-L. Wei, M. J. Costello, and R. K. Colwell (2020). Quantifying sample completeness and comparing diversities among assemblages. Ecological Research, 35, 292-314.

Corresponding BibTeX entry:

  @Article{,
    title = {Quantifying sample completeness and comparing diversities
      among assemblages.},
    author = {{Anne Chao} and {Yasuhiro Kubota} and {David Zelený} and
      {Chun-Huo Chiu} and {Ching-Feng Li} and {Buntarou Kusumoto} and
      {Moriaki Yasuhara} and {Simon Thorn} and {Chih-Lin Wei} and {Mark
      J. Costello} and {Robert K. Colwell}},
    journal = {Ecological Research},
    year = {2020},
    month = {3},
    volume = {35},
    issue = {2},
    pages = {292-314},
    doi = {10.1111/1440-1703.12102},
  }