United Nations Industrial Development Organization. (1972). The manufacture and utilizatin of portland cement. New York: United Nations.
Dyfyniad Arddull ChicagoUnited Nations Industrial Development Organization. The Manufacture and Utilizatin of Portland Cement. New York: United Nations, 1972.
Dyfyniad MLAUnited Nations Industrial Development Organization. The Manufacture and Utilizatin of Portland Cement. New York: United Nations, 1972.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.