To cite package 'spcosa' in publications use:

Dennis Walvoort [aut, cre, cph], Dick Brus [aut, cph], Jaap de Gruijter [aut, cph] (2013). Spatial Coverage Sampling and Random Sampling from Compact Geographical Strata. R package version 0.3-5. http://CRAN.R-project.org/package=spcosa

de Gruijter, J., Brus, D., Bierkens, M. and Knotters, M. (2006) Sampling for Natural Resource Monitoring. Springer, Berlin, ISBN 978-3-540-22486-0

Brus, D. J., Spatjens, L. E. E. M., and de Gruijter, J. J. (1999) A sampling scheme for estimating the mean extractable phosphorus concentration of fields for environmental regulation Geoderma 89: 129-148

Walvoort, D. J. J., Brus, D. J., and de Gruijter, J. J. (2010) An R package for spatial coverage sampling and random sampling from compact geographical strata by k-means Computers & Geosciences 36: 1261-1267 Available online at http://dx.doi.org/10.1016/j.cageo.2010.04.005

See de Gruijter et. al. (2006) and Walvoort et al. (2010) for an introduction to spatial coverage sampling and its applications. Refer to Walvoort et al. (2013) for the spcosa package. See Brus et. al. (1999) for stratified simple random sampling for composites.

Corresponding BibTeX entries:

  @Manual{,
    title = {Spatial Coverage Sampling and Random Sampling from Compact
      Geographical Strata},
    author = {Dennis Walvoort and Dick Brus and Jaap de Gruijter},
    year = {2013},
    note = {R package version 0.3-5},
    url = {http://CRAN.R-project.org/package=spcosa},
  }
  @Book{,
    title = {Sampling for Natural Resource Monitoring},
    author = {J. de Gruijter and D. Brus and M. Bierkens and M.
      Knotters},
    publisher = {Springer},
    address = {Berlin},
    year = {2006},
    note = {ISBN 978-3-540-22486-0},
  }
  @Article{,
    title = {A sampling scheme for estimating the mean extractable
      phosphorus concentration of fields for environmental regulation},
    author = {D. J. Brus and L. E. E. M. Spatjens and J. J. de
      Gruijter},
    journal = {Geoderma},
    year = {1999},
    volume = {89},
    pages = {129--148},
  }
  @Article{,
    title = {An R package for spatial coverage sampling and random
      sampling from compact geographical strata by $k$-means},
    author = {D. J. J. Walvoort and D. J. Brus and J. J. de Gruijter},
    journal = {Computers & Geosciences},
    year = {2010},
    volume = {36},
    pages = {1261--1267},
    note = {Available online at
      http://dx.doi.org/10.1016/j.cageo.2010.04.005},
  }