@book { Erziehungskurse,
    title = "Erziehungskurse",
    author = "Karl-Heinz {Walter}",
    year = "2009",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836627719",
    url = "https://m.diplom.de/document/226670"
}