To cite package 'longpower' in publications use:

Michael C Donohue, (2019). longpower: Power and sample size calculations for longitudinal data. R package version 1.0-19.

Diggle PJ, Heagerty PJ, Liang K, Zeger SL. Analysis of longitudinal data. Second Edition. Oxford Statistical Science Serires. 2002.

Liu, G., & Liang, K. Y. (1997). Sample size calculations for studies with correlated observations. Biometrics, 53(3), 937-47.

Lu, K., Luo, X. & Chen, P. (2008). Sample Size Estimation for Repeated Measures Analysis in Randomized Clinical Trials with Missing Data. The International Journal of Biostatistics, 4(1).

Corresponding BibTeX entries:

  @Manual{,
    title = {longpower: Power and sample size calculations for linear
      mixed models},
    author = {Michael C. Donohue},
    year = {2019},
    note = {R package version 1.0-19},
  }

  @Book{,
    title = {Analysis of longitudinal data},
    author = {P. J. Diggle and P. J. Heagerty and K. Y. Liang and S. L.
      Zeger},
    year = {2002},
    edition = {Second Edition},
    publisher = {Oxford Statistical Science Serires},
  }

  @Article{,
    title = {Sample size calculations for studies with correlated
      observations},
    author = {G. Liu and K. Y. Liang},
    year = {1997},
    journal = {Biometrics},
    volume = {53(3)},
    pages = {937-47},
  }

  @Article{,
    title = {Sample size estimation for repeated measures analysis in
      randomized clinical trials with missing data},
    author = {K. Lu and X. Luo and P.-Y. Chen},
    year = {2008},
    journal = {International Journal of Biostatistics},
    volume = {4(1)},
    pages = {937-47},
  }