  @Manual{R-base,
    title = {R: A Language and Environment for Statistical Computing},
    author = {{R Core Team}},
    organization = {R Foundation for Statistical Computing},
    address = {Vienna, Austria},
    year = {2016},
    url = {https://www.R-project.org/}
  }

  @Misc{NCDC,
    author = {{United States National Oceanic and Atmospheric Administration National Climatic Data Center}},
    title = {{Global Surface Summary of Day (GSOD)}},
    month = {August},
    year = {2016},
    howpublished = {\url{https://data.noaa.gov/dataset/global-surface-summary-of-the-day-gsod}},
    lastchecked = {10/08/2016}},
  }

  @Manual{rnoaa,
    title = {rnoaa: 'NOAA' Weather Data from R},
    author = {Scott Chamberlain},
    year = {2016},
    note = {R package version 0.5.6},
    url = {https://CRAN.R-project.org/package=rnoaa},
  }

  @Misc{Jarvis2008,
    title = {{Hole-filled SRTM for the globe Version 4, available from the CGIAR-CSI SRTM 90m Database}},
    author = {Andy Jarvis and Hannes I Reuter and Andy Nelson and Edward Guevara},
    year = {2008},
    url = {http://srtm.csi.cgiar.org}
  }

  @Manual{GSODR,
    title = {{GSODR}: Global Summary Daily Weather Data in R},
    author = {Adam Sparks and Tomislav Hengl and Andrew Nelson},
    year = {2017},
    note = {R package version 1.0.1},
    url = {http://ropensci.github.io/GSODR/},
  }

  @Misc{geopackage,
    author = {{Open Geospatial Consortium}},
    title = {GeoPackage Encoding Standard},
    url = {http://www.opengeospatial.org/standards/geopackage},
    year = {2014}
  }

  @Manual{readr,
    title = {readr: Read Tabular Data},
    author = {Hadley Wickham and Jim Hester and Romain Francois},
    year = {2016},
    note = {R package version 1.0.0},
    url = {https://CRAN.R-project.org/package=readr},
  }

  @Manual{data.table,
    title = {data.table: Extension of Data.frame},
    author = {M Dowle and A Srinivasan and T Short and S Lianoglou with contributions from R Saporta and E Antonyan},
    year = {2015},
    note = {R package version 1.9.6},
    url = {https://CRAN.R-project.org/package=data.table},
  }

  @Article{plyr,
    title = {The Split-Apply-Combine Strategy for Data Analysis},
    author = {Hadley Wickham},
    journal = {Journal of Statistical Software},
    year = {2011},
    volume = {40},
    number = {1},
    pages = {1--29},
    url = {http://www.jstatsoft.org/v40/i01/},
  }
