Selenium

ChemGlobe: Selenium
Electronic, thermal, and steric data along with an isotope table.
http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/34.html

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

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

It's Elemental: Selenium
Basic physical and historical information.
http://education.jlab.org/itselemental/ele034.html

LANL: Selenium
Production, properties, isotopes, and handling.
http://periodic.lanl.gov/elements/34.html

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

Linking Selenium Sources to Ecosystems: Local and Global Perspectives
U.S. Geological Survey materials on the environmental sources, biogeochemistry, and toxicology of selenium.
http://wwwrcamnl.wr.usgs.gov/Selenium/Index.htm

Selenium Watch
Information resource on adverse health and environmental effects from increased use of selenium by industry, maintained by a non-profit consortium of scientists, researchers and engineers.
http://www.seleniumwatch.org/

USGS Minerals Information: Selenium
Statistics and information on the worldwide supply, demand, and flow of the element (PDF format).
http://minerals.usgs.gov/minerals/pubs/commodity/selenium/

Visual Elements: Selenium
Image, general and physical information, source, uses, key isotopes, and ionisation energies.
http://www.chemsoc.org/viselements/pages/selenium.html

WebElements: Selenium
Extensive information on history, uses, occurrence, compounds, and properties of the element.
http://www.webelements.com/webelements/elements/text/Se/key.html

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

Radiochemistry of Selenium
Full text of the monograph by V. J. Molinski (Union Carbide Corporation, Mining and Metals Division, Research Center, Tuxedo, New York) and G. W. Leddicotte (Oak Ridge National Laboratory, Oak Ridge, Tennessee). [PDF] <small>(November, 1965)</small>
http://library.lanl.gov/cgi-bin/getfile?rc000058.pdf