Unknown Author
Portland Cement Association.
Augusto A. Enteiche G.
William Paul Andrews
P. T. Sherwood
John L. Provis
Donald A. Bruce
Paulo Sá
National Research Council (U.S.). Highway Research Board.
Misión Andina del Ecuador.
Dimcho Evstatiev
Portland Cement Association
Arlen Lee Borgen
United Nations. Dept. of Economic and Social Affairs.
Beatrix Jungman
C. D. Rogers
Ara Arman