@Book{bly2011irrenhaus,
  author = {Bly, Nellie},
  title  = {Zehn Tage im Irrenhaus : Undercover in der Psychiatrie},

  year   = {2011},
  number = {},
  url    = {http://d-nb.info/1011794527/04},

  const  = {\ text}
}
@Book{hader2010empirische,
  author = {Häder, Michael},
  title  = {Empirische Sozialforschung : eine Einführung},

  year   = {2010},
  number = {},
  url    = {http://deposit.d-nb.de/cgi-bin/dokserv?id=3378344&prov=M&dok_var=1&dok_ext=htm},

  const  = {\ text}
}