Title from web page last updated Sept. 10, 2009 (viewed on Nov. 19, 2009).
"This site will no longer receive updates. Please visit the new MRCTR ('Mercator') GIS Lab web site"--Web page (viewed Mar. 8, 2016).
Mode of access: Internet from the U.S. Geological Survey web site. Address as of 11/19/09: http://webgis.wr.usgs.gov/; current access is available via PURL.