//-->
Die Verstaatlichung des Güterfernverkehrs in Grossbritannien
Helsberg, Helmut, (1960)
The transport problem
Foster, Christopher D., (1963)
The economics and control of road-rail competition : A critical study of theory and practice in the United States of America, Great Britain, and Australia
Kolsen, Helmut Max, (1968)
The choice between cars and buses on urban roads
Sharp, C. H., (1967)
"Congestion and welfare" reconsidered
Sharp, C. H., (1968)
Congestion and welfare : a reply
Sharp, C. H., (1969)