Potassium

ChemGlobe: Potassium - Electronic, thermal, and steric data along with basic information.
partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/19.html

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

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

It's Elemental: Potassium - Basic physical and historical information.
education.jlab.org/itselemental/ele019.html

LANL: Potassium - Sources, uses, properties, and isotopes.
periodic.lanl.gov/elements/19.html

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

Visual Elements: Potassium - Image, animation, source, uses, physical information, and key isotopes.
www.chemsoc.org/viselements/pages/potassium.html

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

Radiochemistry of Potassium - Full text of the monograph by William T. Mullins and G. W. Leddicotte (Oak Ridge National Laboratory, Oak Ridge, Tennessee). [PDF] <small>(November, 1961)</small>
lib-www.lanl.gov/cgi-bin/getfile=3frc000016.pdf