Lanthanum

ChemGlobe: Lanthanum - Electronic, steric, and thermal data along with an isotopes table.
partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/57.html

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

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

It's Elemental: Lanthanum - Basic physical and historical information.
education.jlab.org/itselemental/ele057.html

LANL: Lanthanum - Sources, properties, isotopes, and uses.
periodic.lanl.gov/elements/57.html

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

Visual Elements: Lanthanum - Image, appearance, source, uses, and general and physical information.
www.chemsoc.org/viselements/pages/lanthanum.html

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