Homomorphisms of modules associated with polynomial matrices with   infinite elementary divisors
  If the inverse of a nonsingular polynomial matrix $L$ has a polynomial part then one can associate with $L$ a module over the ring of proper rational functions, which is related to the structure of $L$ at infinity. In this paper we characterize homomorphisms of such modules. 
Pudji Astuti, Harald K. Wimmer
math.RA math.AC