@article {Heuvelink2001Geoderma,
	title = {{Modelling soil variation: past, present, and future}},
	journal = {Geoderma},
	volume = {100},
	number = {3-4},
	year = {2001},
	pages = {269-301},
	author = {Heuvelink, G.~B.~M. and Webster, R.}
}