South-west Arabia (The Yemen and the Aden Protectorate) Transliteration of names Third edition [revised by Lt-Col M C Lake] System-RGS II London: Colonial Office, Oct 1941
Record of the expedition to Abyssinia Compiled by order of the Secretary of State for War by Maj Trevenen J Holland and Cpt Henry M Hozier under the direction of Col Sir Henry James etc London: HMSO, 1870 2 vols
Brief notes on the history of the tribes now residing in the Eastern Aden Protectorate, and their present area and divisions, as at Oct 1, 1952 (corrected to 1 July 1955) Maj I E Snell, with 2 appendices by Cpt J N Ellis, Brief notes on the way of life and economic conditions of the different tribes of the Eastern Aden Protectorate as at Oct 1 1952 (corrected to 1 July 1955) Maj I E Snell Aden, 1955 typ