     citHeader("To cite package 'longpower' in publications use:")
     
     year <- sub(".*(2[[:digit:]]{3})-.*", "\\1", meta$Date)
     vers <- paste("R package version", meta$Version)
     
     citEntry(entry="Manual",
              title = "longpower: Power and sample size calculators for linear mixed models",
              author = personList(as.person("Michael C. Donohue"), as.person("Anthony C. Gamst"), as.person("Steven D. Edland")),
              year = year,
              note = vers,
     
              textVersion =
              paste("Michael C Donohue, Steven D Edland (",
                    year,
                    "). longpower: Power and sample size calculators for longitudinal data. ",
                    vers, ".", sep=""))

     citEntry(entry="book",
              title = "Analysis of longitudinal data",
              author = personList(as.person("P. J. Diggle"),
                                  as.person("P. J. Heagerty"),
                                  as.person("K. Y. Liang"),
                                  as.person("S. L. Zeger")),
              year = 2002,
              edition = "Second Edition",
              publisher = "Oxford Statistical Science Serires",
              textVersion = "Diggle PJ, Heagerty PJ, Liang K, Zeger SL. Analysis of longitudinal 
                             data. Second Edition. Oxford Statistical Science Serires. 2002.")

     citEntry(entry="article",
              title = "Sample size calculations for studies with correlated observations",
              author = personList(as.person("G. Liu"),
                                  as.person("K. Y. Liang")),
              year = 1997,
              journal = "Biometrics",
              volume = "53(3)",
              pages = "937-47",
              textVersion = "Liu, G., & Liang, K. Y. (1997). Sample size calculations for studies with correlated observations. Biometrics, 53(3), 937-47.")
