ChemGlobe: Rhodium: Electronic, thermal, and steric data along with an isotope table.
ChemicalElements.com: Rhodium: Basic information, atomic structure, and isotopes.
EnvironmentalChemistry.com: Rhodium: Atomic structure, chemical and physical properties, and table of nuclides.
It's Elemental: Rhodium: Basic physical and historical information.
LANL: Rhodium: History, sources, properties, and uses.
Lenntech: Rhodium: Physical data, chemical properties, health and environmental effects.
Radiochemistry of Rhodium: Full text of the monograph by James Armstrong (Florida State University, Tallahassee, Florida). [PDF]
Rhodium: Data tables and historic information.
Visual Elements: Rhodium: General and physical information, source, uses, key isotopes, and ionisation energies.
WebElements: Rhodium: Extensive information on history, uses, occurrence, compounds, and properties.
Wikipedia: Rhodium: Properties of the element, including its history, applications, and characteristics.