ChemGlobe: Phosphorus
   Electronic, thermal, and steric data along with basic information.
   http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/15.html

ChemicalElements.com: Phosphorus
   Basic information, atomic structure, and table of isotopes.
   http://www.chemicalelements.com/elements/p.html

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

It's Elemental: Phosphorus
   Basic physical and historical information.
   http://education.jlab.org/itselemental/ele015.html

LANL: Phosphorus
   Properties, handling, production, and uses.
   http://periodic.lanl.gov/elements/15.html

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

Radiochemistry of Phosphorus
   Full text of the monograph by William T. Mullins and G. W. Leddicote (Oak Ridge National Laboratory, Oak Ridge, Tennessee). [PDF]
   http://lib-www.lanl.gov/cgi-bin/getfile?rc000024.pdf

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

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