Theobald, R. (1961). The challenge of abundance. New York: C. N. Potter.
Dyfyniad Arddull ChicagoTheobald, Robert. The Challenge of Abundance. New York: C. N. Potter, 1961.
Dyfyniad MLATheobald, Robert. The Challenge of Abundance. New York: C. N. Potter, 1961.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.