Andreas Kühne, "Copernicanism" (translated from German by Andrea Katherina-Mayer), in Arne Hessenbruch, ed., Reader's Guide to the History of Science Taylor & Francis, 2000, p. 152. ISBN9781884964299[2]
jstor.org
Edward Rosen, "Copernicus' Attitude Toward the Common People, Journal of the History of Ideas, 32(April–June 1971)2: 281.[1]
wikipedia.org
de.wikipedia.org
With the spelling with pp used by the astronomer himself in most cases, especially in official documents. Based on over two dozen signatures of the astronomers, of which more than 74% use the spelling with two p, Prowe and Curtze came to the conclusion that the form Coppernicus is the best form to represent the chosen name of the astronomer (and the form Koppernick for his family). - Maximilian Curtze: Ueber die Orthographie des Namens Coppernicus., in the foreword to Nicolaus Coppernicus aus Thorn über die Kreisbewegungen der Weltkörper, 1879 (from German wikisource)
