@book{PetschniggSimeonovMairingeretal.2014,
  author    = {Ursula Petschnigg and Emil Simeonov and Daniela Mairinger and Christian Schmid},
  title     = {Portfolio f{\"u}r den Mathematikunterricht an Bildungsanstalten f{\"u}r Kindergartenp{\"a}dagogik},
  year      = {2014},
}