Gordon, R. L. (1987). World coal: Economics, policies, and prospects. Cambridge University Press.
Lua i Stíl Chicago (17ú heag.)Gordon, Richard L. World Coal: Economics, Policies, and Prospects. Cambridge [Cambridgeshire]: Cambridge University Press, 1987.
Lua MLA (9ú heag.)Gordon, Richard L. World Coal: Economics, Policies, and Prospects. Cambridge University Press, 1987.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.