National Research Council (U.S.). Highway Research Board. (1951). Highways with a narrow median: Presented at the Thirtieth Annual Meeting, 1951. Highway Research Board.
Dyfyniad Arddull ChicagoNational Research Council (U.S.). Highway Research Board. Highways with a Narrow Median: Presented at the Thirtieth Annual Meeting, 1951. Washington, D.C: Highway Research Board, 1951.
Dyfyniad MLANational Research Council (U.S.). Highway Research Board. Highways with a Narrow Median: Presented at the Thirtieth Annual Meeting, 1951. Highway Research Board, 1951.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.