Title: Zīj-i Ulugh Beg, Zīj-i Jadīd-i Sulṭānī or Zīj-i Gurgānī. In the introduction, Ulugh Beg acknowledges the collaboration of Qāḍīzāde, al-Kāshī and al-Qūshjī. It consists of 4 chapters dealing with chronology, trigonometry and spherical astronomy, planetary positions, and astrology respectively. Ulugh Beg’s Zīj was highly influential and continued to be used in the Islamic world until the 19th c. [BEA, van Dalen]