ChemGlobe: Molybdenum - Electronic, thermal, and steric data along with an isotope table.
ChemicalElements.com: Molybdenum - Basic information, atomic structure, and table of isotopes.
EnvironmentalChemistry.com: Molybdenum - Atomic structure, chemical and physical properties, and table of nuclides.
It's Elemental: Molybdenum - Basic physical and historical information.
LANL: Molybdenum - History, sources, uses, and properties.
Lenntech: Molybdenum - Physical data, chemical properties, health and environmental effects.
USGS Minerals Information: Molybdenum - Statistics and information on the worldwide supply, demand, and flow of the element (PDF format).
Visual Elements: Molybdenum - Image, general and physical information, source, uses, key isotopes, and ionisation energies.
WebElements: Molybdenum - Extensive information on history, uses, occurrence, compounds, and properties.
Wikipedia: Molybdenum - Properties of the element, including its history, applications, and characteristics.
Radiochemistry of Molybdenum - Full text of the monograph by E. M. Scadden (U.S. Naval Radiological Defense Laboratory, San Francisco, California). [PDF] (January, 1960)