Não informado. (1919). American Gas Association monthly. American Gas Association.
Chicago-referens (17:e uppl.)Não informado. American Gas Association Monthly. Arlington, Va: American Gas Association, 1919.
MLA-referens (8:e uppl.)Não informado. American Gas Association Monthly. American Gas Association, 1919.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.