Columbia University Library MS Or 49, Kitāb Uṣūl al-handasah wa-al-ḥisāb, كتاب اصول الهندسة والحساب, arabic translation of Euclid's Elements by Nasir ad Din at Tusi copied in the mid- to late-19th century fol 22v, figure I.47 fol 37, figure II.14 fol 49v, figure III.35 fol 50v, figure III.37 fol 54, figures IV.9 et IV.10 fol 55v, figure IV.12 et variante fols 56 à 57 : figure IV.13 et variante fol 68, figure VI.1 et variante fol 77v, figures VI.27 et VI.28 fol 135v, figure XI.31 fol 155, figure XIII.10 fol 160, figure XIII.17 fol 161, figure XIII.18 translations of Euclid's Elements by Nasir ad Din at Tusi Columbia University Library Σ © α