APA-referens (7:e uppl.)

(1953). Farm forestry extension: What it is and how it works / W.K. Williams.

Chicago-referens (17:e uppl.)

Farm Forestry Extension: What It Is and How It Works / W.K. Williams. 1953.

MLA-referens (9:e uppl.)

Farm Forestry Extension: What It Is and How It Works / W.K. Williams. 1953.