ChemicalElements.com: Platinum
Basic information, atomic structure, and isotopes.
EnvironmentalChemistry.com: Platinum
Atomic structure, chemical and physical properties, and table of nuclides.
It's Elemental: Platinum
Basic physical and historical information.
Lenntech: Platinum
Physical data, chemical properties, health and environmental effects.
Radiochemistry of Platinum
Full text of the monograph by G. W. Leddicotte (Oak Ridge National Laboratory, Oak Ridge, Tennessee). [PDF]
Visual Elements: Platinum
Image, general and physical information, source, uses, key isotopes, and ionisation energies.
WebElements: Platinum
Extensive information on history, uses, occurrence, compounds, and properties.
Wikipedia: Platinum
Properties of the element, including its history, applications, and characteristics.