1. Columbia University Rare Book & Manuscript Library, MS Or 25 Bookmark DS ID: DS6484 Title: De sphaericis Author: Theodosius of Bithynia Place: India Date: between 1850 and 1899?
2. Columbia University Rare Book & Manuscript Library, MS Or 28 Bookmark DS ID: DS6600 Title: De sphaericis Author: Theodosius of Bithynia Date: 1800-1899