We construct a family of ideals representing ideal classes of order 2 in quadratic number fields and show that relations between their ideal classes are governed by certain cyclic quartic extensions of the rationals.
Diophantine approximation with prime denominator in quadratic number fields under GRH
On quaternion algebras that split over quadratic number fields
Sign changes of Fourier coefficients of cusp forms of half-integral weight over split and inert primes in quadratic number fields
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