A. Voinov, International Institute for Geo-information Science and Earth Observation (ITC) P.O. Box 6, 7500AA Enschede, The Netherlands
http://www.likbez.com/AV
D. Swayne, Computing Research Laboratory for the Environment, CIS Department, University of Guelph, N1G 2W1, Canada
http://www.crle.uoguelph.ca/dswayne