It is assumed that Jordanus did work in the first part of the thirteenth century (or even in the late twelfth) since his works are contained in a booklist, the "Biblionomia" of Richard de Fournival, compiled between 1246 and 1260.• Edward Grant, “Jordanus de Nemore,” in "Dictionary of Scientific Biography", ed. Charles C. Gillispie (New York: Scribners, 1973), 7: 171-179; • Edward Grant, “Jordanus de Nemore,” in "Medieval Science, Technology, and Medicine. An Encyclopedia", ed. Thomas Glick, et al. (New York: Routledge, 2005), pp. 294-295; • Barnabas B. Hughes, “Biographical Information on Jordanus de Nemore to Date,” "Janus" 62 (1975), 151-156; • Ron B. Thomson, "Jordanus de Nemore and the Mathematics of Astrolabes: De Plana Spera" (Toronto: Pontifical Institute of Mediaeval Studies, 1978), chapter 1: “Jordanus the Mathematician.”</ref>