@articleFouvry_Klüners_2010, title=On the negative Pell equation, volume=172, DOI=10.4007/annals.2010.172.2035, number=3, journal=Annals of Mathematics, publisher=Annals of Mathematics, author=Fouvry, Étienne and Klüners, Jürgen, year=2010, pages=2035–2104