LANL: Iron - History, sources, uses, and properties.
Lenntech: Iron - Physical data, chemical properties, health and environmental effects.
USGS Minerals Information: Iron - Statistics and information on the worldwide supply, demand, and flow of the element (PDF format).
Visual Elements: Iron - Image, general and physical information, source, uses, key isotopes, and ionisation energies.
WebElements: Iron - Extensive information on history, uses, occurrence, compounds, and properties of the element.
Wikipedia: Iron - Properties of the element, including its history, applications, and characteristics.
Radiochemistry of Iron - Full text of the monograph by J. M. Nielsen (Hanford Laboratories, Hanford Atomic Products Operation, Richland, Washington). [PDF] (August, 1960)