Graver, B. (1999). Advanced English practice (third edition.). New york: Cambridge University Press.
Dyfyniad Arddull ChicagoGraver, B.D. Advanced English Practice. third edition. New york: Cambridge University Press, 1999.
Dyfyniad MLAGraver, B.D. Advanced English Practice. third edition. New york: Cambridge University Press, 1999.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.