@Book{gudjons2006unterrichtskultur,
  author = {Gudjons, Herbert},
  title  = {Neue Unterrichtskultur - veränderte Lehrerrolle},

  year   = {2006},
  number = {},
  url    = {http://scans.hebis.de/HEBCGI/show.pl?17854811_toc.pdf},

  const  = {\ text}
}