Jones, L. (1986). Progress to proficiency: Student's book. Cambridge: Cambridge Univ. Press.
Dyfyniad Arddull ChicagoJones, Leo. Progress to Proficiency: Student's Book. Cambridge: Cambridge Univ. Press, 1986.
Dyfyniad MLAJones, Leo. Progress to Proficiency: Student's Book. Cambridge: Cambridge Univ. Press, 1986.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.