ChemGlobe: Gallium
   Electronic, thermal, and steric data along with an isotope table.
   http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/31.html

ChemicalElements.com: Gallium
   Basic information, atomic structure, and isotopes.
   http://www.chemicalelements.com/elements/ga.html

Discovery of Gallium
   Article by P.E. Lecoq de Boisbaudran.
   http://dbhs.wvusd.k12.ca.us/webdocs/Chem-History/Disc-of-Gallium.html

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

It's Elemental: Gallium
   Basic physical and historical information.
   http://education.jlab.org/itselemental/ele031.html

LANL: Gallium
   Sources, properties, uses, and costs.
   http://periodic.lanl.gov/elements/31.html

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

USGS Minerals Information: Gallium
   Statistics and information on the worldwide supply, demand, and flow of the element. [PDF]
   http://minerals.usgs.gov/minerals/pubs/commodity/gallium/

Visual Elements: Gallium
   General and physical information, key isotopes, and ionisation energies.
   http://www.chemsoc.org/viselements/pages/gallium.html

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