ChemGlobe: Vanadium: Electronic, thermal, and steric data along with an isotope table.
ChemicalElements.com: Vanadium: Basic information, atomic structure, and isotopes.
EnvironmentalChemistry.com: Vanadium: Atomic structure, chemical and physical properties, and table of nuclides.
It's Elemental: Vanadium: Basic physical and historical information.
LANL: Vanadium: History, sources, uses, and properties.
Lenntech: Vanadium: Physical data, chemical properties, health and environmental effects.
Radiochemistry of Vanadium: Full text of the monograph by J. L. Brownlee Jr. (Dept. of Chemistry, University of Michigan, Ann Arbor, Michigan). [PDF]
USGS Minerals Information: Vanadium: Statistics and information on the worldwide supply, demand, and flow of the element (PDF format).
Vanadium: Data tables and historic information.
Visual Elements: Vanadium: General and physical information, source, uses, key isotopes, and ionisation energies.
WebElements: Vanadium: Extensive information on history, uses, occurrence, compounds, and properties of the element.
Wikipedia: Vanadium: Properties of the element, including its history, applications, and characteristics.