Morita equivalences induced by bimodules over Hopf-Galois extensions
  Let $H$ be a Hopf algebra, and $A,B$ be $H$-Galois extensions. We investigate the category ${}_A\mathcal{M}_B^H$ of relative Hopf bimodules, and the Morita equivalences between $A$ and $B$ induced by them. 
S. Caenepeel, S. Crivei, A. Marcus, M. Takeuchi