Europium

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

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

ChemGlobe: Europium - Electronic, thermal, and steric data along with isotopes table.
http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/63.html

Visual Elements: Europium - Image, source, physical information, and key isotopes.
http://www.chemsoc.org/viselements/pages/europium.html

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

It's Elemental: Europium - Basic physical and historical information.
http://education.jlab.org/itselemental/ele063.html

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

LANL: Europium - History, production, properties, sources, and uses.
http://periodic.lanl.gov/elements/63.html

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