@book { InterventionindemSystemFamilie,
    title = "Intervention in dem System Familie",
    author = "Matthias {Sombold}",
    year = "2008",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836616416",
    url = "https://m.diplom.de/document/225972"
}