Erbium
Links
Visual Elements: Erbium
http://www.chemsoc.org/viselements/pages/erbium.html
Image, physical information, key isotopes, and ionisation energies.
Erbium
http://www.scescape.net/~woods/elements/erbium.html
Includes the history of the element, and a data sheet.
It's Elemental: Erbium
http://education.jlab.org/itselemental/ele068.html
Basic physical and historical information.
ChemicalElements.com: Erbium
http://www.chemicalelements.com/elements/er.html
Basic information, atomic structure, and isotopes.
EnvironmentalChemistry.com: Erbium
http://environmentalchemistry.com/yogi/periodic/Er.html
Atomic structure, chemical and physical properties, and table of nuclides.
WebElements: Erbium
http://www.webelements.com/webelements/elements/text/Er/key.html
Extensive information on history, uses, occurrence, compounds, and properties.
Lenntech: Erbium
http://www.lenntech.com/Periodic-chart-elements/Er-en.htm
Physical data, chemical properties, health and environmental effects.