Specifications for construction of roads and bridges in national forests and national parks 1941® Federal Works Agency, Public Roads Administration,, Washington, U.S.gvmt.prtg.off.,1941® 1941, (Ikke digitaliseret)
Per Fahrzeug-Dieselmotor, sein Bau und Betrieb, seine Pflege und Reparaturen. Hrsg.von W.Haeder [m.fl.J 1941, Peter, M., (Ikke digitaliseret)