@article{UhlendorffKrappmann1999,
  author    = {Uhlendorff, Harald and Krappmann, Lothar},
  title     = {Kinderfreundschaften und Freundschaftskonzept},
  issn      = {1435-4594},
  year      = {1999},
  language  = {de}
}
@article{KrappmannUhlendorffOswald1999,
  author    = {Krappmann, Lothar and Uhlendorff, Harald and Oswald, Hans},
  title     = {Qualities of Children{\"i}s Friendships in Middle Childhood in East- and West Berlin},
  isbn      = {3-11-016500-7},
  year      = {1999},
  language  = {en}
}
@article{KrappmannUhlendorff1999,
  author    = {Krappmann, Lothar and Uhlendorff, Harald},
  title     = {Soziometrische Akzeptanz in der Schulklasse und Kinderfreundschaften},
  isbn      = {3-89271-865-2},
  year      = {1999},
  language  = {de}
}