@book {Olaya2004SAGA,
	title = {{A gentle introduction to SAGA GIS}},
	year = {2004},
	pages = {208},
	publisher = {The {SAGA} User Group e.V.},
	organization = {The {SAGA} User Group e.V.},
	address = {Gottingen, Germany},
	author = {Olaya, V.~F.}
}