J. L. Berggren - Simon Fraser University, Canada

Ab? Sahl W?jan (B?zhan) ibn Rustam al-K?h? the ۱۰th century mathematician and astronomer was from Tabarist?n (present M?zandar?n) province of Iran. Apart from his rich legacy kept in several manuscripts and studied, edited and translated widely, we know that some of his works have been lost. In this article, K?h?’s lost mathematical works are traced through references and quotations in the works of other scholars, especially his contemporary al-Sijz?, and K?h? himself.