Johnson, R. (1996). Elementary statistics (7th ed.). Duxbury.
Dyfyniad Arddull ChicagoJohnson, Robert. Elementary Statistics. 7th ed. Belmont: Duxbury, 1996.
Dyfyniad MLAJohnson, Robert. Elementary Statistics. 7th ed. Duxbury, 1996.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.