Xenon

Especiál Gas Inc.: Xenon - Numeric data, uses, and general information.
http://www.c-f-c.com/specgas_products/xenon.htm

ChemicalElements.com: Xenon - Basic information, atomic structure, and table of isotopes.
http://www.chemicalelements.com/elements/xe.html

ChemGlobe: Xenon - Electronic, thermal, and steric data along with an isotope table.
http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/54.html

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

It's Elemental: Xenon - Basic physical and historical information.
http://education.jlab.org/itselemental/ele054.html

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

LANL: Xenon - Basic information, history, isotopes, and uses.
http://periodic.lanl.gov/elements/54.html

EnvironmentalChemistry.com: Xenon - Atomic structure, properties, and table of nuclides.
http://environmentalchemistry.com/yogi/periodic/Xe.html

Visual Elements: Xenon - General and physical information, source, uses, key isotopes, and ionisation energies.
http://www.chemsoc.org/viselements/pages/xenon.html

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