@book { MagenundDarmerkrankungennatrlichbehandeln,
    title = "Magen- und Darmerkrankungen natürlich behandeln",
    author = "Dr. Andrea {Flemmer}",
    year = "2011",
    publisher = "Schlütersche Verlagsgesellschaft mbH & Co. KG",
    address = ", Deutschland",
    url = "https://schluetersche.openpublishing.com/document/403590"
}