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

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

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

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

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

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

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

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