Jacob, M. (1974). Dual theory. North-Holland Publishing Company.
Dyfyniad Arddull ChicagoJacob, M. Dual Theory. Amsterdam: North-Holland Publishing Company, 1974.
Dyfyniad MLAJacob, M. Dual Theory. North-Holland Publishing Company, 1974.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.