Astatine

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

WebElements: Astatine - Extensive information on history and properties.
http://www.webelements.com/webelements/elements/text/At/key.html

It's Elemental: Astatine - Basic physical and historical information.
http://education.jlab.org/itselemental/ele085.html

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

ChemGlobe: Astatine - Electronic, thermal, and steric data, along with a table of isotopes.
http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/85.html

Britannica Nobel Prize: Astatine - Overview and basic data.
http://www.britannica.com/nobel/micro/38_12.html

Radiochemistry of Astatine - Full text of the monograph by Evan H. Appelman (Argonne National Laboratory, Lemont, Illinois). [PDF] <small>(March, 1960)</small>
http://library.lanl.gov/cgi-bin/getfile?rc000018.pdf

Chemical Elements.com: Astatine - Basic information, atomic structure, and table of isotopes.
http://www.chemicalelements.com/elements/at.html

LANL: Astatine - History, uses, production, and properties.
http://periodic.lanl.gov/elements/85.html

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

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