Petrus Apianus, German scholar (real name Bienewitz or Bennewitz; born at Leisnig, 1495; professor at the University of Ingolstadt, where he died, 21 April 1552), published in 1524 at Landshut his famous treatise on cosmography, the Cosmographicus liber. Gemma Frisius (Gemma Reyneri or Jemme Reinersz, named Frisius after his native province of Frisia: Dokkum, 1508 - Louvain, 1555), physician, mathematician, astronomer, and cosmographer, professor at the University of Louvain, published in 1529 a new edition with many additions and corrections. This revised Cosmographicus liber met with a tremendous success and was many times reprinted, eventually with new additions. Cf. F. van Ortroy, 'Bibliographie de l'oeuvre de Pierre Apian' in Bibliographie moderne, 1901, pages 89-335.