1. IO Islamic 824/4 Reference (shelfmark): IO Islamic 824/4 Title: [Risālah fī al-ḥisāb] Scope & Content: Author: Ṭūsī, Naṣīr al-Dīn Muḥammad ibn Muḥammad, 1201-1274 VIAF ID: 12392936 Subject: Mathematics, Arab--Early works to 1800 Collection Area: Oriental Manuscripts Languages: Arabic Date Range: 1134 Extent: 1 item