Astatine

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

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

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

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

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

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

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

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