ChemicalElements.com: Ruthenium
Basic information, atomic structure, and table of isotopes.
EnvironmentalChemistry.com: Ruthenium
Atomic structure, chemical and physical properties, and table of nuclides.
It's Elemental: Ruthenium
Basic physical and historical information.
Lenntech: Ruthenium
Physical data, chemical properties, and health effects.
Ruthenium
Data tables and historic information.
Visual Elements: Ruthenium
Image, discovery, uses, source, and physical information.
WebElements: Ruthenium
Extensive information on history, uses, occurrence, compounds, and properties.
Wikipedia: Ruthenium
Properties of the element, including its history, applications, and characteristics.