Organisations:
F.A.I. Fédération Aéronautique Internationale (FAI), the world’s air sports federation
Museums:
Deutsches Museum München
Deutsches Technik-Museum Berlin
Engine-overhaul in Königswinter with Argus-Certificate
Manuals and Catalogues about almost all german aircraft in Hafner’s aeronautical archive
Collectors and internet-sites:
Everything about Cockpit-Instruments of german aircraft
Peanut Scale He 64 as model (please view!) with the respective drawings and 3 side-views