citHeader("To cite package 'spgrass6' in publications use your choice of:")
     
if(!exists("meta") || is.null(meta))
    meta <- packageDescription("spgrass6")
year <- sub("-.*", "", meta$Date)
note <- sprintf("R package version %s", meta$Version)
     
citEntry(entry = "Manual",
         title = "{spgrass6}: Interface between GRASS 6 and R",
         author = personList(as.person("Roger Bivand")),
         year = year,
         note = note,
         url = "http://CRAN.R-project.org/package=spgrass6",

         textVersion = paste("Roger Bivand (", year, 
             "). spgrass6: Interface between GRASS 6 and R. ",
             note, ".", sep=""))

citEntry(entry = "Article",
         title = "Using the {R}--{GRASS} Interface: Current Status",
         author = personList(as.person("Roger Bivand")),
         year = "2007",
         journal = "{OSGeo} Journal",
         volume = "1",
         pages = "36--38",
         url = "http://www.osgeo.org/files/journal/final_pdfs/OSGeo_vol1_GRASS-R.pdf",

         textVersion = paste("Roger Bivand (2007",
             "). Using the {R}--{GRASS} Interface: Current Status. ",
             "OSGeo Journal, 1, pp. 36-38", sep=""))

citEntry(entry = "Book",
         title = "Applied Spatial Data Analysis with {R}",
         author = personList(as.person("Roger S. Bivand"),
                             as.person("Edzer J. Pebesma"),
                             as.person("Virgilio Gomez-Rubio")),
         year = "2008",
         publisher = "Springer",
         address = "New York",
         textVersion = paste("Roger S. Bivand, Edzer J. Pebesma and Virgilio Gomez-Rubio",
             " (2008) Applied Spatial Data Analysis with R. ",
             "Springer, New York.", sep=""))

citEntry(entry = "Book",
         title = "Open Source {GIS}: a {GRASS} {GIS} Approach",
         author = personList(as.person("Markus Neteler"),
                             as.person("Helena Mitasova")),
         year = "2008",
         publisher = "Springer",
         address = "New York",
         textVersion = paste("Markus Neteler and Helena Mitasova",
             " (2008) Open Source GIS: a GRASS GIS Approach. ",
             "Springer, New York.", sep=""))

