Unknown Author
Charles Hamilton Hoyt
Hubert Chanson
Donald E. Metzler
California Highways and Public Works.
National Research Council (U.S.) Transportation Research Board
J. D. Helvey
Armco Drainage and Metal Products, inc.
National Research Council (U.S.). Transportation Research Board
Albert H. Mirati
American Railway Engineering Association
Voravit Lertlaksana
Canada. Restrictive Trade Practices Commission
California. Dept. of Public Works.
Alfred C. Scheer
Malcolm Harvey Karr
United States Steel Corporation