Layard, R. (1994). Cost-benefit analysis (2nd ed.). Cambridge University Press.
Dyfyniad Arddull ChicagoLayard, Richard. Cost-benefit Analysis. 2nd ed. Cambridge: Cambridge University Press, 1994.
Dyfyniad MLALayard, Richard. Cost-benefit Analysis. 2nd ed. Cambridge University Press, 1994.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.