Bell Measurements and Observables
  A general matrix approach to study entangled states is presented, based on operator completeness relations. Bases of unitary operators are considered, with focus on irreducible representations of groups. Bell measurements for teleportation are considered, and robustness of teleportation to various kinds of non idealities is shown. 
G. M. D'Ariano, P. Lo Presti, M. F. Sacchi