To cite package 'longpower' in publications use:

Michael C Donohue, Steven D Edland (2016). longpower: Power and sample size calculators for longitudinal data. R package version 1.0-16.

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.

Corresponding BibTeX entries:

@Manual{, title = {longpower: Power and sample size calculators for linear mixed models}, author = {Michael C. Donohue and Anthony C. Gamst and Steven D. Edland}, year = {2016}, note = {R package version 1.0-16}, }

@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}, }