ChemGlobe: Chromium - Electronic, thermal, and steric data along with an isotopes table. - http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/24.html
LANL: Chromium - History, sources, uses, and compounds. - http://periodic.lanl.gov/elements/24.html
Wikipedia: Chromium - Properties of the element, including its history, applications, and characteristics. - http://en.wikipedia.org/wiki/Chromium
Lenntech: Chromium - Physical data, chemical properties, health and environmental effects. - http://www.lenntech.com/Periodic-chart-elements/Cr-en.htm
EnvironmentalChemistry.com: Chromium - Atomic structure, chemical and physical properties, and table of nuclides. - http://environmentalchemistry.com/yogi/periodic/Cr.html
Visual Elements: Chromium - General and physical information, source, uses, key isotopes, and ionisation energies. - http://www.chemsoc.org/viselements/pages/chromium.html
USGS Minerals Information: Chromium - Statistics and information on the worldwide supply, demand, and flow of the element (PDF format). - http://minerals.usgs.gov/minerals/pubs/commodity/chromium/
Radiochemistry of Chromium - Full text of the monograph by J. Pijck (Laboratory for Analytical Chemistry, University of Ghent, Ghent, Belgium). - http://lib-www.lanl.gov/cgi-bin/getfile?rc000002.pdf