Haines & Maassen Metallhandelsgesellschaft mbH
Die Firma liefert so genannte Nebenmetalle wie Hafnium, Indium, Gallium, Niob, Wismut, Tantal, Wolfram und Hafnium sowie entsprechende Legierungen und Halbzeug. [D-53225 Bonn]
http://www.haines-maassen-metallhandel.de/

LANL: Hafnium
History, properties, uses, and handling.
http://periodic.lanl.gov/elements/72.html

It's Elemental: Hafnium
The Element Hafnium - Basic Physical and Historical Information
http://education.jlab.org/itselemental/ele072.html

Britannica Nobel Prize: Hafnium
Detailed overview and data.
http://www.britannica.com/nobel/micro/254_6.html

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

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

ChemGlobe: Hafnium
The chemical element [Hf] - Hafnium - Datasheet
http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/72.html

EnvironmentalChemistry.com: Hafnium
Comprehensive information for the element Hafnium – Hf is provided by this page including scores of properties, element names in many languages, most known nuclides and technical terms are linked to their definitions.
http://environmentalchemistry.com/yogi/periodic/Hf.html

Lenntech: Hafnium
chemical properties, health and environmental effects of hafnium
http://www.lenntech.com/Periodic-chart-elements/Hf-en.htm

Visual Elements: Hafnium
General and physical information, source, uses, key isotopes, and ionisation energies.
http://www.chemsoc.org/viselements/pages/hafnium.html