@incollection {spies1999, title = {Analyzing particle movements at soil interfaces}, volume = {3: Systems and Applications}, year = {1999}, pages = {699-718}, publisher = {Academic Press}, chapter = {32}, author = {Hagen Spies and Oliver Beringer and Hermann Gr{\"o}ning and Horst Hau{\ss}ecker and Bernd J{\"a}hne and Horst Hau{\ss}ecker and Peter Gei{\ss}ler} }