Barker, J. L. NEMA standards for traffic control systems. Traffic engineering : official publication of the Institute of Transportation Engineers.
Citazione stile Chigago Style (17a edizione)Barker, John L. "NEMA Standards for Traffic Control Systems." Traffic Engineering : Official Publication of the Institute of Transportation Engineers .
Citatione MLA (9a ed.)Barker, John L. "NEMA Standards for Traffic Control Systems." Traffic Engineering : Official Publication of the Institute of Transportation Engineers, .
Attenzione: Queste citazioni potrebbero non essere precise al 100%.