Praseodymium

ChemGlobe: Praseodymium
Electronic, thermal, and steric data along with an isotope table.
http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/59.html

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

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

It's Elemental: Praseodymium
Basic physical and historical information.
http://education.jlab.org/itselemental/ele059.html

LANL: Praseodymium
History, uses, production, and properties.
http://periodic.lanl.gov/elements/59.html

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

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

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

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