Exploration of Every Known Atom in the Universe. New York: Black Dog & Leventhal Publishers. 2009. ISBN 978-1-57912-814-2. Committee On Radiation Source
Exploration of Every Known Atom in the Universe. New York: Black Dog & Leventhal Publishers. 2009: 240. ISBN 978-1-57912-814-2. Lanthanide 互联网档案馆的存檔,存档日期11
[2009-08-08]. (原始内容存档于2019-01-30). Gray, Theodore. The Elements. Black Dog & Leventhal Pub. 2010. ISBN 978-1-57912-895-1. Greenwood and Earnshaw, pp. 1235–8