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WebElements: Erbium - http://www.webelements.com/webelements/elements/text/Er/key.html
Extensive information on history, uses, occurrence, compounds, and properties. |
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Wikipedia: Erbium - http://en.wikipedia.org/wiki/Erbium
Properties of the element, including its history, applications, and characteristics. |
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LANL: Erbium - http://periodic.lanl.gov/elements/68.html
Basic information and history. |
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It's Elemental: Erbium - http://education.jlab.org/itselemental/ele068.html
Basic physical and historical information. |
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ChemicalElements.com: Erbium - http://www.chemicalelements.com/elements/er.html
Basic information, atomic structure, and isotopes. |