1. Austen, Ralph A. ‘The Islamic Slave Trade out of Africa (Red Sea and Indian Ocean): An Effort at Quantification’. Conference on ‘Islamic Africa: Slavery and Related Institutions’. 14 June. Princeton University.
2. ‘The Islamic Red Sea Slave Trade: An Effort at Quantification,’. Proceedings of the Fifth International Conference on Ethiopian Studies. pp.443–67. Chicago: U. of Illinois. ibid.
3. THE ETHIOPIAN SLAVE TRADE IN THE NINETEENTH AND EARLY TWENTIETH CENTURIES: A STATISTICAL INQUIRY