Nicolaus Copernicus Prussia also resisted the Polish crown's efforts for greater control over the region. "Encyclopædia Britannica", "Encyclopedia Americana", "The Concise Columbia Encyclopedia", "The Oxford World Encyclopedia", and "World Book Encyclopedia" refer to Copernicus as a "Polish astronomer". Sheila Rabin, writing in the "Stanford Encyclopedia of Philosophy", describes Copernicus as a "child of a German family [who] was a subject of the Polish crown", while Manfred Weissenbacher writes that Copernicus's father was a Germanized Pole. There are additional arguments for Kopernik's Polish descent on his father's side. Kopernik's Y-DNA haplogroup, R1b L51, is found in southern Poland (in Silesia, where his father
Nicolaus Copernicus Fracastoro, Gabriele Zerbi, Alessandro Benedetti—and read medical treatises that he acquired at this time, by Valescus de Taranta, Jan Mesue, Hugo Senensis, Jan Ketham, Arnold de Villa Nova, and Michele Savonarola, which would form the embryo of his later medical library. One of the subjects that Copernicus must have studied was astrology, since it was considered an important part of a medical education. However, unlike most other prominent Renaissance astronomers, he appears never to have practiced or expressed any interest in astrology. As at Bologna, Copernicus did not limit himself to his official studies. It was probably the Padua years