@unpublished{Murr2012,
  author  = {R{\"u}diger Murr},
  title   = {Reciprocal classes of Markov processes : an approach with duality formulae},
  institution = {Institut f{\"u}r Mathematik},
  series    = {Preprints des Instituts f{\"u}r Mathematik der Universit{\"a}t Potsdam},
  number    = {1(2012)26},
  year    = {2012},
}