@book {Rossiter2007ITCck,
	title = {{Technical Note: Co-kriging with the gstat package of the R environment for statistical computing}},
	year = {2007},
	pages = {81},
	publisher = {International Institute for Geo-information Science \& Earth Observation (ITC)},
	organization = {International Institute for Geo-information Science \& Earth Observation (ITC)},
	edition = {2.1},
	address = {Enschede, Netherlands},
	author = {Rossiter, D.~G.}
}