@article{OswaldKrappmannUhlendorffetal.1994,
  author    = {Oswald, Hans and Krappmann, Lothar and Uhlendorff, Harald and Weiss, Karin},
  title     = {Social relationships and support among peers during middle childhood},
  year      = {1994},
  language  = {en}
}
@article{OswaldKrappmann1995,
  author    = {Oswald, Hans and Krappmann, Lothar},
  title     = {Social life of children in a former bipartite city},
  year      = {1995},
  language  = {en}
}
@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}
}