De revolutionibus orbium coelestium
Georg Joachim de Porris, also known as Rheticus (; 16 February 1514 – 4 December 1574), was a mathematician, astronomer, cartographer, navigational-instrument maker, medical practitioner, and teacher. He is perhaps best known for his trigonometric tables and as Nicolaus Copernicus's sole pupil. He facilitated the publication of his master's "De revolutionibus orbium coelestium" ("On the Revolutions of the Heavenly Spheres").