Não informado. (1968). Professional Engineer. National Society of Professional Engineers.
Chicago-Zitierstil (17. Ausg.)Não informado. Professional Engineer. Jersey City, NJ: National Society of Professional Engineers, 1968.
MLA-Zitierstil (8. Ausg.)Não informado. Professional Engineer. National Society of Professional Engineers, 1968.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.