Não informado. (1968). Petroleum Review. Institute of Petroleum.
Lua i Stíl Chicago (17ú heag.)Não informado. Petroleum Review. London: Institute of Petroleum, 1968.
Lua MLA (8ú heag.)Não informado. Petroleum Review. Institute of Petroleum, 1968.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.