Working paper - Institute of Transportation Studies, University of California ; no. UCB-ITS-WP-79-5 Working paper - Institute of Transportation Studies, University of California ; UCB-ITS-WP-79-8 Adolf D. May ; Institute of Transportation Studies University of California. Institute of Transportation Studies University of California. Research series - Institute of International Studies, University of California, Berkeley ; Research series - Institute of International Studies, University of California, Berkeley ; no. 35 Research Series - Institute of International Studies, University of California ; Research series - Institute of International Studies, University of California, Berkeley ; no. 36 Research report - Institute of Transportation Studies ; UCB-ITS-RR-79-1 Research report - Institute of Transportation Studies ; UCB-ITS-RR-79-4