Butterman, William C.; Brooks, William E.; Reese, Jr., Robert G. (2004). "Mineral Commodity Profile: Cesium"(PDF). United States Geological Survey. Archived from the original(PDF) on February 7, 2007. Retrieved 2009-12-27.
web.archive.org
Butterman, William C.; Brooks, William E.; Reese, Jr., Robert G. (2004). "Mineral Commodity Profile: Cesium"(PDF). United States Geological Survey. Archived from the original(PDF) on February 7, 2007. Retrieved 2009-12-27.