Radium

Britannica Nobel Prize: Radium - Detailed overview and data.
http://www.britannica.com/nobel/micro/491_93.html

Radiochemistry of Radium - Full text of the monograph by Murrell L. Salutsky (W.R. Grace and Co., Research Division, Washington Research Center, Clarksville, Maryland) and H. W. Kirby (Mound Laboratory, Miamisburg, Ohio). [PDF] <small>(December, 1964)</small>
http://library.lanl.gov/cgi-bin/getfile?rc000041.pdf

Lenntech: Radium - Physical data, chemical properties, health and environmental effects.
http://www.lenntech.com/Periodic-chart-elements/Ra-en.htm

It's Elemental: Radium - Basic physical and historical information.
http://education.jlab.org/itselemental/ele088.html

Visual Elements: Radium - Image, general and physical information, source, uses, key isotopes, and ionisation energies.
http://www.chemsoc.org/viselements/pages/radium.html

LANL: Radium - History, sources, properties, and uses.
http://periodic.lanl.gov/elements/88.html

EnvironmentalChemistry.com: Radium - Atomic structure, chemical and physical properties, and table of nuclides.
http://environmentalchemistry.com/yogi/periodic/Ra.html

ChemicalElements.com: Radium - Basic information, atomic structure, and isotopes.
http://www.chemicalelements.com/elements/ra.html

Wikipedia: Radium - Properties of the element, including its history, applications, and charateristics.
http://en.wikipedia.org/wiki/Radium

ChemGlobe: Radium - Electronic, thermal, and steric data along with an isotope table.
http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/88.html

WebElements: Radium - Extensive information on history, uses, occurrence, compounds, and properties.
http://www.webelements.com/webelements/elements/text/Ra/key.html