Johnson, C. (1986). The practical zone system: A simple guide to photographic control. Focal Press.
Dyfyniad Arddull ChicagoJohnson, Chris. The Practical Zone System: A Simple Guide to Photographic Control. Boston: Focal Press, 1986.
Dyfyniad MLAJohnson, Chris. The Practical Zone System: A Simple Guide to Photographic Control. Focal Press, 1986.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.