HAJJI KHALIFA (Mustafa ibn `Abdallah Katib Chelebi Haj ji Khalifa) (c. ' 599-1658), Arabic and Turkish author, was born at Constantinople. He became secretary to the commis sariat department of the Turkish army in Anatolia, was with the army in Baghdad in 1625 and was present at the siege of Erzerum. In 1633 he made the pilgrimage to Mecca (hence his title Hajji). While serving in the commissariat department at Constantinople, he wrote in Arabic his largest work, the Bibliographical Encyclo paedia. After five chapters dealing with the sciences generally, the titles of Arabian, Persian and Turkish books written up to his own time are arranged alphabetically. Sometimes short notes on the author, his date and the introductory words of his work are given. It was edited by G. Fliigel with Latin translation ( 7 vols. Leipzig, 183 5-58 ), and also at Constantinople (1893).