John Freely, Celestial Revolutionary: Copernicus, the Man and His Universe, I.B. Tauris, 2014, p. 9, ISBN 9789004183629.
«He was named after his father, Niklas Koppernigk, but afterwards followed the academic custom of the time and Latinized his name as Nicolaus Copernicus. The Koppernigk family were originally German-speakers who migrated eastward to the province of Silesia in the thirteenth century, settling in the town known today as Koperniki, in present-day southeast Poland, close to the Czech border.»