@book { Reizdarmsyndromlindern,
    title = "Reizdarmsyndrom lindern",
    subtitle = "Mit der Maria-Holl-Methode (MHM). Der ganzheitliche Ansatz",
    author = "Maria {Holl}",
    year = "2014",
    publisher = "Schlütersche Verlagsgesellschaft mbH & Co. KG",
    address = ", Deutschland",
    url = "https://schluetersche.openpublishing.com/document/403865"
}