(1992). Resources and industry. New York: Oxford University Press.
Dyfyniad Arddull ChicagoResources and Industry. New York: Oxford University Press, 1992.
Dyfyniad MLAResources and Industry. New York: Oxford University Press, 1992.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.