O. Temple 
Notes on the Tribes, Provinces, Emirates and States of the Northern Provinces of Nigeria [PDF ebook] 

First Published in 1965. The compilation contained in the following book have been made with the object of rendering available to those interested, in a small compass, at all events some of the immense stores of facts concerning the natives of the Northern Provinces of Nigeria assiduously collected by the political staff. This information is contained scattered through innumerable reports, assessment reports, annual and monthly reports, and official letters, etc., which are kept at the Secretariat and the Provincial Headquarters, and is not readily accessible, even to those who are stationed at Headquarters and are able to command the Secretariat files.