Johnson, C. (1986). The practical zone system: A simple guide to photographic control. Focal Press.
Lua i Stíl Chicago (17ú heag.)Johnson, Chris. The Practical Zone System: A Simple Guide to Photographic Control. Boston: Focal Press, 1986.
Lua MLA (9ú heag.)Johnson, Chris. The Practical Zone System: A Simple Guide to Photographic Control. Focal Press, 1986.
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