sentences:  Nevertheless, Copernicus cited some of the Islamic astronomers whose theories and observations he used in "De Revolutionibus", namely al-Battani, Thabit ibn Qurra, al-Zarqali, Averroes, and al-Bitruji.When Copernicus' compendium was published, it contained an unauthorized, anonymous preface by a friend of Copernicus, the Lutheran theologian Andreas Osiander.This cleric stated that Copernicus wrote his heliocentric account of the Earth's movement as a mathematical hypothesis, not as an account that contained truth or even probability.