ChemGlobe: Nickel
- Electronic, thermal, and steric data along with an isotope table.
- http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/28.html

LANL: Nickel
- Sources, properties, and uses.
- http://periodic.lanl.gov/elements/28.html

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

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

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

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

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

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

It's Elemental: Nickel
- Basic physical and historical information.
- http://education.jlab.org/itselemental/ele028.html

Radiochemistry of Nickel
- Full text of the monograph by L. J. Kirby (Hanford Atomic Products Operation, Richland, Washington). [PDF]
- http://lib-www.lanl.gov/cgi-bin/getfile?rc000008.pdf