Colvin, C., & Stevenson, J. A. (1922). Farm projects: A textbook in agriculture for seventh and eighth grades and junior high schools. The Macmillan Company.
Lua i Stíl Chicago (17ú heag.)Colvin, Carl, agus John A. Stevenson. Farm Projects: A Textbook in Agriculture for Seventh and Eighth Grades and Junior High Schools. New York: The Macmillan Company, 1922.
Lua MLA (8ú heag.)Colvin, Carl, agus John A. Stevenson. Farm Projects: A Textbook in Agriculture for Seventh and Eighth Grades and Junior High Schools. The Macmillan Company, 1922.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.