Não informado. (1920). Contractors and engineers monthly. Buttenheim-Dix Publishing.
Chicago-referens (17:e uppl.)Não informado. Contractors and Engineers Monthly. New York: Buttenheim-Dix Publishing, 1920.
MLA-referens (8:e uppl.)Não informado. Contractors and Engineers Monthly. Buttenheim-Dix Publishing, 1920.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.