ChemGlobe: Cobalt
- Electronic, thermal, and steric data, along with isotopes table.
- http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/27.html

LANL: Cobalt
- History, sources, properties, and uses.
- http://periodic.lanl.gov/elements/27.html

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

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

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

Visual Elements: Cobalt
- Image, general and physical information, source, uses, biological role, key isotopes, and ionisation energies.
- http://www.chemsoc.org/viselements/pages/cobalt.html

USGS Minerals Information: Cobalt
- Statistics and information on the worldwide supply, demand, and flow of the element (PDF format).
- http://minerals.usgs.gov/minerals/pubs/commodity/cobalt/

ChemicalElements.com: Cobalt
- Basic information, atomic structure, and isotopes.
- http://www.chemicalelements.com/elements/co.html

It's Elemental: Cobalt
- Basic physical and historical information.
- http://education.jlab.org/itselemental/ele027.html

Radiochemistry of Cobalt
- Full text of the monograph by L.C. Bate (Oak Ridge National Laboratory, Oak Ridge, Tennessee). [PDF]
- http://lib-www.lanl.gov/cgi-bin/getfile?rc000054.pdf