Selenium

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

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

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

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

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

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

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

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

Wikipedia: Selenium - Properties of the element, including its history, applications, and characteristics.
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>
lib-www.lanl.gov/cgi-bin/getfile=3frc000058.pdf