@book { NatrlichschmerzfreierRcken,
    title = "Natürlich schmerzfreier Rücken",
    author = "Sofia {Melnik}",
    year = "2016",
    publisher = "humboldt",
    address = "Hannover, Deutschland",
    url = "https://schluetersche.openpublishing.com/document/403971"
}