Northern Region of Nigeria (Nigeria). Public Works Dept. Annual report on the Public works Department of the Northern Region of Nigeria. Govt. Printer.
Chicago-referens (17:e uppl.)Northern Region of Nigeria (Nigeria). Public Works Dept. Annual Report on the Public Works Department of the Northern Region of Nigeria. Kaduna: Govt. Printer.
MLA-referens (8:e uppl.)Northern Region of Nigeria (Nigeria). Public Works Dept. Annual Report on the Public Works Department of the Northern Region of Nigeria. Govt. Printer.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.