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