@article {Heuvelink1999Geoderma,
	title = {{Spatial aggregation and soil process modelling}},
	journal = {Geoderma},
	volume = {89},
	number = {1-2},
	year = {1999},
	pages = {47-65},
	author = {Heuvelink, G.~B.~M. and Pebesma, E.~J.}
}