Virtuelles Kraftfahrzeug Museum Austria (voz.co.at) has information on Austrian marques (including automobiles and other vehicles), and listings for museums and clubs.
Motorradveteranenclub Attnang Puchheim: historical notes on a good number of marques with a focus on those of Germany and Austria.
Motorpaul NL has extensive information on Austro-Omega, York and others.
German translations (word only, not phrase)
by Oxford University
Triumph, BMW, & Kawasaki Sales Spares & Repairs.
Established for over 40 years and run by expert motorcyclists.
Fully authorised workshop.