National Research Council (U.S.). Transportation Research Board. (1990). Continuing project to synthesize information on highway problems. Transportation Research Board, National Research Council.
Dyfyniad Arddull ChicagoNational Research Council (U.S.). Transportation Research Board. Continuing Project to Synthesize Information on Highway Problems. Washington, D.C: Transportation Research Board, National Research Council, 1990.
Dyfyniad MLANational Research Council (U.S.). Transportation Research Board. Continuing Project to Synthesize Information on Highway Problems. Transportation Research Board, National Research Council, 1990.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.