Hybrid bounds for automorphic forms on ellipsoids over number fields
  We prove upper bounds for Hecke-Laplace eigenfunctions on certain Riemannian manifolds of arithmetic type. The manifolds under consideration are d-fold products of 2-spheres or 3-spheres, realized as adelic quotients of quaternion algebras over totally real number fields. 
Valentin Blomer, Philippe Michel
math.NT