Barnard, J. D. (1967). Science: A key to the future. Macmillan.
Lua i Stíl Chicago (17ú heag.)Barnard, J. Darrell. Science: A Key to the Future. New York: Macmillan, 1967.
Lua MLA (9ú heag.)Barnard, J. Darrell. Science: A Key to the Future. Macmillan, 1967.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.