Germanium

Minor Metal Trade Association
Benefits and promotes the interests of its international membership, comprising companies actively involved in all aspects of the international trade of minor metals in all their various forms.
Wikipedia
Open source encyclopedia.
Environmentalchemistry.com
Physical, chemical and historical information.
United States Geological Survey
Germanium Statistics and Information.
Webelements
Basic information on Germanium.
Crystran
Information of use of germanium as an optical window.
Isotopes of Germanium
Information on decay process.
Point Defects in Silicon and Silicon-Germanium
Network of groups in the UK currently working on issues related to point defects in silicon and silicon-germanium.