@unpublished{MuellerKirstenParkRana1999,
  author  = {H. J. W. M{\"u}ller-Kirsten and D.K. Park and J.M.S. Rana},
  title   = {A condition for first order phase transitions in quantum mechanical tunneling models},
  institution = {Fachbereich Physik},
  year    = {1999},
  url  = {http://nbn-resolving.de/urn:nbn:de:hbz:386-kluedo-10194},
}