The effect of the ionosphere on communication, navigation, and surveillance systems : based on Ionospheric Effects Symposium, 5-7 May 1987 /

Mode of access: Internet.

Motorist aid systems study. State of the art report. Final report.

Federal Highway Administration, Office of Development, Washington, D.C.

Variable message signing for traffic surveillance and control - a state of the art report. Final report.

Mode of access: Internet.