LANL: Iridium - History, properties, uses, and sources.
Lenntech: Iridium - Physical data, chemical properties, health and environmental effects.
Visual Elements: Iridium - Image, general and physical information, source, uses, key isotopes, and ionisation energies.
Wikipedia: Iridium - Properties of the element, including its history, applications, and characteristics.
Radiochemistry of Iridium - Full text of the monograph by G. W. Leddicotte (Oak Ridge National Laboratory, Oak Ridge, Tennessee). [PDF] (October, 1961)