Johnson, C. (2007). The practical zone system : for film and digital photography: A simple guide to photographic control (4th ed.). Elsevier/Focal Press.
Chicago-referens (17:e uppl.)Johnson, Chris. The Practical Zone System : For Film and Digital Photography: A Simple Guide to Photographic Control. 4th ed. Boston: Elsevier/Focal Press, 2007.
MLA-referens (9:e uppl.)Johnson, Chris. The Practical Zone System : For Film and Digital Photography: A Simple Guide to Photographic Control. 4th ed. Elsevier/Focal Press, 2007.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.