Simpson, A. (1954). The Nigerian coalfield: The geology of parts of Onitsha, Owerri, and Benue Provinces. By authority of the Nigerian Govt..
Lua i Stíl Chicago (17ú heag.)Simpson, A. The Nigerian Coalfield: The Geology of Parts of Onitsha, Owerri, and Benue Provinces. [Zaria]: By authority of the Nigerian Govt., 1954.
Lua MLA (8ú heag.)Simpson, A. The Nigerian Coalfield: The Geology of Parts of Onitsha, Owerri, and Benue Provinces. By authority of the Nigerian Govt., 1954.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.