Comatrix Corings an Invertible Bimodules
  We extend Masuoka's Theorem [11] concerning the isomorphism between the group of invertible bimodules in a non-commutative ring extension and the group of automorphisms of the associated Sweedler's canonical coring, to the class of finite comatrix corings introduced in [6]. 
L. El Kaoutit and J. Gomez-Torrecillas