Não informado. NASA Classification Change Notices. National Aeronautics and Space Administration.
Chicago-referens (17:e uppl.)Não informado. NASA Classification Change Notices. Washington: National Aeronautics and Space Administration.
MLA-referens (8:e uppl.)Não informado. NASA Classification Change Notices. National Aeronautics and Space Administration.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.