On the reproducing kernel of a Pontryagin space of vector valued   polynomials
  We give necessary and sufficient conditions under which the reproducing kernel of a Pontryagin space of $d \times 1$ vector polynomials is determined by a generalized Nevanlinna pair of $d \times d$ matrix polynomials. 
Branko \'Curgus and Aad Dijksma
math.FA math.AC