ChemGlobe: Ruthenium
   Electronic, thermal, and steric data along with an isotope table.
   http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/44.html

ChemicalElements.com: Ruthenium
   Basic information, atomic structure, and table of isotopes.
   http://www.chemicalelements.com/elements/ru.html

EnvironmentalChemistry.com: Ruthenium
   Atomic structure, chemical and physical properties, and table of nuclides.
   http://environmentalchemistry.com/yogi/periodic/Ru.html

It's Elemental: Ruthenium
   Basic physical and historical information.
   http://education.jlab.org/itselemental/ele044.html

LANL: Ruthenium
   History, sources, uses, and properties.
   http://periodic.lanl.gov/elements/44.html

Lenntech: Ruthenium
   Physical data, chemical properties, and health effects.
   http://www.lenntech.com/Periodic-chart-elements/Ru-en.htm

Visual Elements: Ruthenium
   Image, discovery, uses, source, and physical information.
   http://www.chemsoc.org/viselements/pages/ruthenium.html

Wikipedia: Ruthenium
   Properties of the element, including its history, applications, and characteristics.
   http://en.wikipedia.org/wiki/Ruthenium